Medical tool employing a warning mechanism notifying that a rotational limit has been reached

ABSTRACT

A medical tool includes a rotation mechanism that further includes a warning feature. The warning feature provides an indication when the rotation mechanism has achieved a number of rotations.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of and priority to U.S. ProvisionalPatent Application Ser. No. 62/377,435, filed Aug. 19, 2016, entitled,“MEDICAL TOOL EMPLOYING A WARNING MECHANISM NOTIFYING THAT A ROTATIONALLIMIT HAS BEEN REACHED.”

FIELD OF THE INVENTION

Aspects of the present invention relate to medical apparatus andmethods. More specifically, the present invention relates to a medicaltool for the delivery, implantation, actuation and/or manipulation of animplantable device and/or patient tissue, such as a leadless pacemaker.

BACKGROUND OF THE INVENTION

Leadless pacemakers and their delivery systems are a new technology.Similar to implantable leads that extend from a traditional pacemaker orimplantable cardioverter defibrillator (ICD), there are essentially twofixation mechanisms for anchoring the leadless pacemaker to theendocardium; tines that get pulled into tissue and a helix that isrotated to fixate to cardiac tissue (similar to a screw).

For leadless pacemakers that require rotation for fixation, there are anumber of possible clinical events that can occur as a result of over orunder-rotating the leadless pacemaker. If the leadless pacemaker isunder-rotated, it can come loose prior to full release or migratepost-release.

If the leadless pacemaker is over-rotated, the helix portion of theleadless pacemaker can either penetrate or pinch tissue. Thispenetration/pinching can potentially lead to a variety of adverseclinical events.

There is a need in the art for a system for, and method of, delivering aleadless pacemaker for fixation to cardiac tissue while reducing thepossibility of under/over rotation of the leadless pacemaker duringfixation.

BRIEF SUMMARY OF THE INVENTION

Disclosed herein is a warning mechanism for informing the physicianregarding the number of rotations associated with the fixation of theleadless pacemaker, the warning mechanism being supported on a deliverysystem for the delivery and fixation of the leadless pacemaker tocardiac tissue. In one embodiment, the warning system is supported onthe handle of the delivery system, the handle having a torque portion,which when rotated, causes the leadless pacemaker to rotate.

The purpose of the warning mechanism is to provide the physician withinformation about how many rotations of the leadless pacemaker haveoccurred in the course of trying to anchor the leadless pacemaker tocardiac tissue via the delivery system. When the warning system providesnotice to the physician that a certain number of rotations of theleadless pacemaker have occurred, the physician needs to consciouslythink about progressing further in the procedure.

In order to progress with rotating the leadless pacemaker past the pointwhere the warning mechanism has notified the physician that the certainnumber of rotations has been reached, the physician needs to make aconscious choice to proceed, which can occur in a number of ways,depending on the embodiment of the warning mechanism. For example, thephysician must actuate or disable a feature of the warning mechanism toallow further rotations. Additionally or alternatively, the physicianmust overcome a temporary or short term increase in resistance tobringing about further rotation of the leadless pacemaker. Additionallyor alternatively, the physician may overcome a warning to bring aboutfurther rotation of the leadless pacemaker for a pre-designed number ofadditional implant rotations, or implant partial rotations, whereby thedelivery system torque portion enters a freewheel mode of infiniterotations.

The warning mechanism is advantageous in that it allows for the leadlesspacemaker to be removed and repositioned and yet provide repeatedwarnings to the physician when the certain number of rotations have beenreached, the warning mechanism being resettable or self-resetting toallow for repeated removal/reposition/anchoring of the leadlesspacemaker.

In one embodiment, the warning mechanism informs the physician of acertain level of leadless pacemaker rotations by changing the amount ofeffort needed to continue rotating a torque portion of a handle of thedelivery system for a short period of time. As the torque portion isbeing rotated clockwise (CW) initially, the effort required isrelatively low as a shuttle translates along the handle body. Once theshuttle contacts an O-ring, the effort required to continue rotatingincreases significantly. In order for the physician to continue rotatingthe torque portion and the leadless pacemaker operably coupled to thetorque portion, the physician simply needs to increase rotational forceapplied to the torque portion. As the rotation force applied to thetorque portion is increased, the shuttle could either expand/openslightly and/or the O-ring could be compressed slightly. A thread on ahandle shaft continues to translate the shuttle until the shuttle hascleared the O-ring. Once the shuttle has cleared the O-ring, the effortrequired to rotate the handle returns to normal. The shuttle may coverthe O-ring at this point, but does not interfere with it. Thisnon-interference allows the feel of the torque portion to return tonormal after the O-ring has been cleared. At this point, the user isfree to rotate the handle in the clock-wise direction freely without asecondary warning system, although in some embodiments, additionalO-ring could be employed to give additional incremental warnings.

If the physician needs to re-position the leadless pacemaker, the torqueportion of the handle only needs to be turned in the opposite direction(counter-clockwise (CCW)). In order for the shuttle to properlyre-engage the thread, a spring with sufficient enough force biases theshuttle up against the shaft thread segment of the torque portion of thehandle. When the torque portion gets rotated CCW with the shuttle incontact with the shaft thread segment, the shuttle begins translatingtowards the distal end of the handle. To clear the O-ring, the shuttleagain needs to expand slightly and/or compress the O-ring. Once theshuttle has cleared the O-ring, the physician can continue rotating thetorque portion of the handle with normal effort until the leadlesspacemaker is completely removed from cardiac tissue. Once the physicianhas repositioned the leadless pacemaker to a desired location, themechanism starts over, and will again inform the user at the set torqueportion rotation level as another spring biases the shuttle back intothreaded engagement with the shaft thread segment as the torque portionis rotated CW.

In one embodiment, the system employs bumps on the housing that arecontacted by complementary bumps on the shuttle to provide a warningmechanism that informs the physician of a certain level of leadlesspacemaker rotations by changing the amount of effort needed to continuerotating a torque portion of a handle of the delivery system for a shortperiod of time. The bumps operate similarly to the operation of theO-ring. Specifically, a pair of plastic bumps exists along a shuttletrack. The pair of plastic bumps are contacted at a certain rotationlevel by similar features on the shuttle. In order to move the shuttlepast the shuttle track bumps and continue rotating the torque portion,the user would need to rotate the torque portion with greater/consciouseffort. Once the interference/bump is cleared, the torque portion of thehandle would return to normal with respect to rotational feel.

In one embodiment, the warning mechanism informs the physician of thehandle rotation level by providing a hard or soft stop at a certainnumber of turns of the torque portion of the handle in place of, oradditional to, employing the O-ring or bumps. A helical partial threadon the shaft translates a shuttle towards the proximal end. When therotation limit is reached, the shuttle comes in contact with amechanical or electro-mechanical obstacle, which physically prevents itfrom translating further, and subsequently prevents the torque portionof the handle from further rotating the shaft and, by extension, theleadless pacemaker. In order for the physician to continue rotating thetorque portion and the leadless pacemaker, the physician needs tointentionally displace the switch to remove the obstacle inhibiting theshuttle. Once the switch is displaces, the shuttle is again free totranslate, which allows the torque portion and leadless pacemaker torotate freely.

After the switch is displaced, if the physician needs to unscrew theleadless pacemaker and re-position the leadless pacemaker, the physiciansimply rotates the handle in the other direction. By rotating the torqueportion of the handle in the CCW direction, the shuttle re-engages thehelical partial thread on the shaft and will translate distally until itis back at its starting point. The user would then return the switch toits starting point in order for the warning mechanism to function asecond time as the shuttle is moved proximally as the torque portion ofthe handle is rotated CW.

Disclosed herein is a medical tool. In one embodiment, the tool includesa handle, a torque portion, a shuttle, and a warning mechanism. Thetorque portion is operably coupled to the housing and rotatable relativeto the housing. The torque portion includes a shaft including an outercircumferential surface and a helical thread portion radially outwardlyextending from the outer circumferential surface of the shaft. Theshuttle is displaceable along the shaft via threaded interaction withthe helical thread portion. The warning mechanism interacting with theshuttle provides a tactile indication when the torque portion hasrotated a number of rotations.

The warning mechanism may include an O-ring on the shaft that isdeflected by the shuttle as the shuttle passes over the O-ring, thedeflection providing the tactile indication. For example, the O-ring maybe deflected by a lip of the shuttle. Also, the shuttle may include aregion inward of the lip that allows the O-ring to return to itsnon-deflected shape within the confines of the shuttle. The tactileindication may include a period of increased rotational resistance atthe torque portion as the O-ring is being deflected by the shuttle.

The warning mechanism may include a structural feature on the housingthat is contacted by a structural feature on the shuttle as the shuttledisplaces along the shaft. For example, the structural feature on thehousing may include a bump, and the structural feature on the shuttlemay include a bump, at least one of the bumps deflecting as the shuttledisplaces along the shaft, the deflection providing the tactileindication. The tactile indication may include a period of increasedrotational resistance at the torque portion as the at least one of thebumps is being deflected.

The warning mechanism may include a hard stop contactable by the shuttlenear a proximal end of the displacement of the shuttle along the shaft,the tactile indication being provided by the shuttle contacting the hardstop. The hard stop can be moved out of alignment with the shuttle suchthat the shuttle can be further proximally displaced along the shaft.

The shaft may include a first end and a second end opposite the firstend. The shaft may be capable of infinite rotation in a first directionwithout causing further displacement of the shuttle along the shafttoward the first end when the shuttle is at a first location near thefirst end. Also, rotation of the shaft in a second direction oppositethe first direction when the shuttle is at the first location causes theshuttle to displace along the shaft towards the second end.

The shaft may also be capable of infinite rotation in the seconddirection without causing further displacement of the shuttle along theshaft toward the second end when the shuttle is at a second locationnear the second end. Also, rotation of the shaft in the first directionwhen the shuttle is at the second location causes the shuttle todisplace along the shaft towards the first end.

The tool may also include a first biasing element that biases theshuttle towards the second end when the shuttle is at the firstlocation, and a second biasing element that biases the shuttle towardsthe first end when the shuttle is at the second location.

Disclosed herein is a medical tool. In one embodiment, the tool includesa rotation mechanism including a warning feature that provides a tactileindication when the rotation mechanism has achieved a number ofrotations.

In one embodiment, the tactile indication is provided by interferencebetween parts of the rotation mechanism. For example, the interferencemay be between an O-ring on a shaft of the rotation mechanism that iscompressed by a shuttle that displaces along the shaft and is driven bythe shaft. As another example, the interference may be between a shuttleof the rotation mechanism and a handle housing of the medical tool.

In one embodiment, the tactile indication includes a period of increasedrotational resistance at a torque portion of a handle of the tool.

In one embodiment, the tactile indication may be provided by a shaftdriven shuttle of the rotation mechanism contacting a hard stop alignedwith the shuttle. The hard top can be placed out of alignment with theshuttle to allow further displacement of the shuttle.

In one embodiment, a drive shaft of the rotation mechanism includes afirst end and a second end opposite the first end. The drive shaft iscapable of infinite rotation in a first direction without causingfurther displacement of the shuttle along the drive shaft toward thefirst end when the shuttle is at a first location near the first end.Rotation of the drive shaft in a second direction opposite the firstdirection when the shuttle is at the first location causes the shuttleto displace along the drive shaft towards the second end.

The drive shaft is capable of infinite rotation in the second directionwithout causing further displacement of the shuttle along the driveshaft toward the second end when the shuttle is at a second locationnear the second end. Rotation of the drive shaft in the first directionwhen the shuttle is at the second location causes the shuttle todisplace along the drive shaft towards the first end.

A first biasing element of the rotation mechanism biases the shuttletowards the second end when the shuttle is at the first location. Asecond biasing element of the rotation mechanism biases the shuttletowards the first end when the shuttle is at the second location.

Also disclosed herein is a delivery system. In one embodiment, thedelivery system includes a handle, a torque portion, a shuttle, and awarning mechanism. The torque portion is operably coupled to the housingand rotatable relative to the housing. The torque portion includes ashaft including an outer circumferential surface and a helical threadportion radially outwardly extending from the outer circumferentialsurface of the shaft. The shuttle is displaceable along the shaft viathreaded interaction with the helical thread portion. The electronicwarning mechanism interacting with the shuttle provides an indicationwhen the torque portion has rotated a number of rotations. Theindication provided by the warning mechanism may be, among other things,a visual, audial, or tactile indication. In one embodiment, the numberof rotations is determined based on a variable resistance element thatinteracts with the shuttle such that as the shuttle is displaced alongthe shaft, a resistance of the variable resistance element changes. Inanother embodiment, the number of rotations is determined by a switchdisposed in the housing that is actuated when the shuttle reaches apredetermined position along the shaft corresponding to the number ofrotations of the shaft.

While multiple embodiments are disclosed, still other embodiments of thepresent disclosure will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative embodiments of the disclosure. As will be realized, theinvention is capable of modifications in various aspects, all withoutdeparting from the spirit and scope of the present disclosure.Accordingly, the drawings and detailed description are to be regarded asillustrative in nature and not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of an example of a leadless pacemakerdelivery system employing the rotation mechanism disclosed herein.

FIG. 2 is an isometric view of the proximal region of the leadlesspacemaker delivery system, which includes a handle employing therotation mechanism disclosed herein.

FIG. 3 is the same view as FIG. 2, except with a portion of a housing ofthe handle removed to reveal the rotation mechanism enclosed therein.

FIG. 4 is an exploded isometric view of the handle and rotationmechanism enclosed therein.

FIG. 5 is a longitudinal cross section of the handle and rotationmechanism enclosed therein as viewed along section line 5-5 in FIG. 2.

FIG. 6 is an isometric view of a torque portion of the handle.

FIGS. 7A and 7B are opposite isometric views of a ratchet assembly ofthe rotation mechanism.

FIGS. 8A and 8B are opposite isometric views of a shuttle of therotation mechanism.

FIGS. 9A and 9B are opposite isometric views of a stop ring of therotation assembly.

FIG. 9C is a side plan view of a modification to the stop ring of FIGS.9A and 9B.

FIG. 10A is an isometric view of the handle with a portion of a housingremoved to reveal the rotation mechanism enclosed therein, the shuttlebeing in a most distal location along a shaft of the torque portion ofthe handle.

FIG. 10B is a longitudinal cross-section of the rotation mechanism inthe region identified in FIG. 10A and as taken along section line10B-10B in FIG. 10A.

FIG. 11A is the same view as FIG. 10A, except the shuttle is in aproximal location along the shaft of the torque portion of the handleand an abutment of the shuttle abuts against a hard stop of a stop ring.

FIG. 11B is a longitudinal cross-section of the rotation mechanism inthe region identified in FIG. 11A and as taken along section line11B-11B in FIG. 11A.

FIG. 12A is the same view as FIG. 11A, except the shuttle is in a mostdistal location along the shaft of the torque portion of the handle, alever of the stop ring having been used to rotate the stop ring about alongitudinal axis of the shaft of the torque portion of the handle suchthat the hard stop of the stop ring is rotated so as to be clear of theabutment of the shuttle, the shuttle thereby being free to proceed moreproximally than depicted in FIG. 11A.

FIG. 12B is a longitudinal cross-section of the rotation mechanism inthe region identified in FIG. 12A and as taken along section line12B-12B in FIG. 12A.

FIG. 13 is an isometric view of the handle of the leadless pacemakerdelivery system, except employing another version of the rotationmechanism disclosed herein, wherein a portion of a housing of the handleis removed to reveal the rotation mechanism enclosed therein.

FIG. 14 is a longitudinal cross section of the handle and rotationmechanism enclosed therein as viewed along section line 14-14 in FIG.14.

FIG. 15A is an isometric view of the handle with a portion of a housingremoved to reveal the rotation mechanism enclosed therein, the shuttlebeing in a most distal location along a shaft of the torque portion ofthe handle and the springs being hidden for clarity purposes.

FIG. 15B is a longitudinal cross-section of the rotation mechanism inthe region identified in FIG. 15A and as taken along section line15B-15B in FIG. 15A.

FIG. 16A is the same view as FIG. 15A, except the shuttle is in aproximal location along the shaft of the torque portion of the handleand a proximal lip of a proximal chamber of the shuttle has just beganto contact a distal boundary of the O-ring.

FIG. 16B is a longitudinal cross-section of the rotation mechanism inthe region identified in FIG. 16A and as taken along section line16B-16B in FIG. 16A.

FIG. 17A is the same view as FIG. 16A, except the O-ring has cleared theproximal lip of the proximal chamber of the shuttle and been fullyreceived in the most proximal region of the proximal chamber of theshuttle.

FIG. 17B is a longitudinal cross-section of the rotation mechanism inthe region identified in FIG. 17A and as taken along section line17B-17B in FIG. 17A.

FIG. 18A is the same view as FIG. 17A, except the shuttle is in a mostproximal location along the shaft of the torque portion of the handle,the O-ring having been fully received in the most distal region of theproximal chamber of the shuttle, the O-ring abutting against the distallip of the chamber.

FIG. 18B is a longitudinal cross-section of the rotation mechanism inthe region identified in FIG. 18A and as taken along section line18B-18B in FIG. 18A.

FIG. 19 is an isometric view of half of the shuttle employed in a thirdversion of the rotation mechanism.

FIG. 20 is an isometric view of a half of a proximal end of the housingthat is immediately adjacent the torque portion of the handle, as can beunderstood by comparison to FIG. 4.

FIG. 21 is a plan view of the half of the housing of the leadlesspacemaker delivery system, except employing another version of therotation mechanism disclosed herein.

FIG. 22 is a bottom plan view of the rotation mechanism and housing.

FIG. 23 is a longitudinal cross sectional view of the leadless pacemakerdelivery system, except employing another version of the rotationmechanism.

FIG. 24A is an isometric view of the handle of the leadless pacemakerdelivery system, except employing another version of the rotationmechanism disclosed herein, wherein a portion of a housing of the handleis removed to reveal the rotation mechanism enclosed therein.

FIG. 24B is a longitudinal cross section of the handle and rotationmechanism enclosed therein as viewed along section line 24B-24B in FIG.24A with the shuttle in a first position.

FIG. 25 is a longitudinal cross section of the handle and rotationmechanism enclosed therein as viewed along section line 24B-24B in FIG.24A with the shuttle in a second position.

FIG. 26 is a longitudinal cross section of the handle and rotationmechanism enclosed therein as viewed along section line 24B-24B in FIG.24A with the shuttle in a third position.

FIG. 27 is an isometric view of the handle of the leadless pacemakerdelivery system, except employing another version of the rotationmechanism disclosed herein, wherein a portion of a housing of the handleis removed to reveal the rotation mechanism enclosed therein.

FIGS. 28A-28B are longitudinal cross sectional views of the handle ofthe leadless pacemaker delivery system to reveal the rotation mechanismenclosed therein, except employing another version of the rotationmechanism disclosed herein.

FIGS. 29A-29H are graphs illustrating feedback profiles that may beachieved in different embodiments of the leadless pacemaker deliverysystems disclosed herein.

DETAILED DESCRIPTION

Implementations of the present disclosure involve a medical toolincluding a rotation mechanism having a warning feature that provides atactile indication when the rotation mechanism has achieved a number ofrotations. The tactile indication may be provided via, for example,deflection or compression of a resilient member such as an O-ring.

Alternatively or additionally, the tactile indication may be provided byinterference of structural members contacting each other, such as bumpson one element being brought into contact with bumps on another element,one or more of the bumps being caused to deflect on account of thecontact.

Alternatively or additionally, the tactile indication may be providedvia abutting contact between elements of the rotation mechanism, such ascontact between a hard contact of a stop ring and a surface of ashuttle. The hard contact of the stop ring may be rotated out ofalignment with the surface of the shuttle to facilitate resumeddisplacement of the shuttle.

The rotation mechanism is advantageous as it may be configured forinfinite rotation in a first direction when the shuttle is at a firstlocation on a shaft of the rotation mechanism, and infinite rotation ina second direction opposite the first direction when the shuttle is at asecond location on the shaft opposite the first location. Further, theshuttle may biased such that rotation in the second direction when theshuttle is at the first location results in displacement of the shuttletowards the second location, and rotation in the first direction whenthe shuttle is at the second location results in displacement of theshuttle towards the first location.

Before discussing the specifics of the rotation mechanism and thewarning features disclosed here, a discussion will now be providedregarding an example medical tool employing the rotation mechanism andthe warning features.

A. Overview of Example Tool Embodiments Employing the Rotation Mechanism

The rotation mechanism 90 disclosed herein and discussed in detail belowmay be beneficially employed in a wide variety medical tools. Forexample, in one embodiment, the rotation mechanism 90 may be employed inthe handle 108 of a leadless pacemaker delivery system 100 configured todeliver into a patient a leadless pacemaker 102 such as the Nanostim™leadless pacemaker as manufactured by Abbott.

Typically, a leadless pacemaker is substantially enclosed in a hermetichousing suitable for placement on or attachment to the inside or outsideof a cardiac chamber. Depending on the embodiment, the pacemaker canhave two or more electrodes located within, on, or near the housing, fordelivering pacing pulses to muscle of the cardiac chamber and optionallyfor sensing electrical activity from the muscle, and for bidirectionalcommunication with at least one other device within or outside the body.The housing can contain a primary battery to provide power for pacing,sensing, and communication, for example bidirectional communication. Thehousing can optionally contain circuits for sensing cardiac activityfrom the electrodes. The housing contains circuits for receivinginformation from at least one other device via the electrodes andcontains circuits for generating pacing pulses for delivery via theelectrodes. The housing can optionally contain circuits for transmittinginformation to at least one other device via the electrodes and canoptionally contain circuits for monitoring device health. The housingcontains circuits for controlling these operations in a predeterminedmanner.

In some embodiments, a leadless pacemaker can be adapted for deliveryand implantation into tissue in the human body. In a particularembodiment, a leadless pacemaker can be adapted for implantationadjacent to heart tissue on the inside or outside wall of a cardiacchamber, using two or more electrodes located on or within the housingof the pacemaker, for pacing the cardiac chamber upon receiving atriggering signal from at least one other device within the body.

Self-contained or leadless pacemakers or other biostimulators aretypically fixed to an intracardial implant site by an actively engagingmechanism or primary fixation mechanism such as a screw or helicalmember that screws into the myocardium. Examples of such leadlessbiostimulators are described in the following publications, thedisclosures of which are incorporated by reference herein in theirentireties: (1) U.S. Pat. No. 8,457,742; (2) U.S. application Ser. No.11/549,581 filed on Oct. 13, 2006, entitled “Leadless CardiacPacemaker”, and published as US2007/0088396A1 on Apr. 19, 2007; (3) U.S.application Ser. No. 11/549,591, filed on Oct. 13, 2006, entitled“Leadless Cardiac Pacemaker System with Conductive Communication” andpublished as US2007/0088397A1 on Apr. 19, 2007; (4) U.S. Pat. No.8,352,025; (5) U.S. Pat. No. 7,937,148; (6) U.S. Pat. No. 7,945,333; (7)U.S. Pat. No. 8,010,209; and (8) International Application No.PCT/US2006/040564, filed on Oct. 13, 2006, entitled “Leadless CardiacPacemaker and System” and published as WO07047681A2 on Apr. 26, 2007.

Leadless pacemakers or biostimulators can be delivered to, and retrievedfrom, a patient using a delivery system 100 similar to that describedbelow with respect to FIG. 1, which is an isometric view of the deliverysystem 100. As illustrated in FIG. 1, the delivery system 100 caninclude a guide catheter sheath 111 including an atraumatic distal end104 in the form of a pacemaker sheath 104. The delivery system 100 canalso have a pacemaker introducer sheath 107 and a catheter shaft 106.The catheter shaft 106 includes at its proximal end the handle 108, adeflection knob 110, and a tether shuttle 112. Each of the longitudinalbodies 107, 111, 106 includes a flush port 114 a, 114 b, 114 c extendingrespectively therefrom. As can be understood from FIG. 1, the cathetershaft 106 extends through the guide catheter sheath 111, which extendsthrough the introducer sheath 107. Each of the longitudinal bodies 106,107, 111 are displaceable proximal-distal relative to each other.

As discussed in detail in U.S. Publication No. 20160096001, which isentitled “DELIVERY CATHETER SYSTEMS AND METHODS,” filed Oct. 7, 2014,hereby incorporated by reference in its entirety herein, in oneembodiment, the atraumatic pacemaker sheath 104 may have a braided orwoven construction that is sufficiently flexible to allow the atraumaticpacemaker sheath 104 to encompass the leadless pacemaker 102 or to havea diameter that is smaller than a diameter of the leadless pacemaker 102when not encompassing the leadless pacemaker 102. The deflection knob110 can be used to deflect the catheter shaft 106 within the cathetersheath 111 to steer and guide the catheter during implantation and/orremoval of the pacemaker. The flush ports 114 a, 114 b, and 114 c can beused to flush saline or other fluids through the catheter. Theatraumatic sheath 104 forms the distal most region of the cathetersheath 111. The catheter sheath 111 can be advanced distally over thecatheter shaft 106 such that the atraumatic sheath 104 is caused toextend over the leadless pacemaker 102. Also, the distal displacement ofcatheter sheath 111 relative to the catheter shaft 106 can be used toprovide additional steering and support for the delivery catheter duringimplantation and to surround the pacemaker as it is introduced through atrocar or the introducer sheath 107 into the patient. The cathetersheath 111 can be retracted proximally over the catheter shaft 106 suchthat the atraumatic sheath 104 is caused to retract from over theleadless pacemaker 102, the braided construction of atraumatic sheath104 being such that the atraumatic sheath 104 self-biases into a reduceddiameter. The reduced diameter of the atraumatic sheath 104 is nogreater than the diameter of the leadless pacemaker 102.

As can be understood from FIG. 1 and the above-referencedpatent/applications, a leadless pacemaker 102 is attached or connectedto a distal end of the delivery system 100 and advanced intravenouslyinto the heart. As discussed in greater detail below, the rotationmechanism 90 incorporated in the handle 108 of the delivery system 100can be used to cause a linear member 120 that extends longitudinallythrough the catheter shaft 106 and is operably coupled to the rotationmechanism 90 to rotate relative to the catheter shaft 106 about thelongitudinal axis of the catheter shaft 106 to rotate the leadlesspacemaker 102 about its longitudinal axis such that the distal helicalanchor of the leadless pacemaker 102 screws into the cardiac tissue ifthe leadless pacemaker 102 is being implanted or to unscrew from thecardiac tissue if the leadless pacemaker 102 is being explanted.

Each of the rotation mechanisms 90 discussed below employ a rotationlimit warning mechanism by which a physician is notified that aprescribed number of rotations of the helical anchor of the leadlesspacemaker has been reached. Upon having received the rotation limitwarning, the physician may elect to continue to further rotate thehelical anchor in the direction of tissue anchoring, to leave the anchoras is with respect to direction and number of rotations, or torotationally withdraw the helical anchor and again attempt to rotate thehelical anchor into the cardiac tissue.

B. Handle with Rotation Mechanism Employing Stop Ring Rotation LimitWarning

As shown in FIG. 2, which is an isometric view of the proximal region ofthe leadless pacemaker delivery system of FIG. 1, the handle 108includes a housing portion 125 and a torque portion 130, which may be inthe form of a torque knob 130. The housing portion 125 encloses therotation mechanism 90 and is coupled to the catheter shaft 106. Thetorque portion 130 is operably coupled to the housing portion 125 suchthat the torque portion 130 can rotate relative to the housing portion125 about a common longitudinal axis of the two portions 125, 130.

As described in detail below, rotation of the torque portion 130relative to the housing portion 125 drives the rotation mechanism 90 tocause a similar rotation of the linear member 120 relative to thecatheter shaft 106, the linear member 120 being operably coupled to therotation mechanism 90.

As depicted in FIG. 2, in one embodiment, the torque portion 125 isproximal the distal housing portion 125. However, in other embodiments,the arrangement may be reversed proximal-distal.

As illustrated in FIG. 3, which is the same view as FIG. 2, except witha half-shell of the housing portion 125 of the handle 108 removed toreveal the rotation mechanism 90 enclosed therein, the housing portion125 may be a multi-piece construction that forms a shell that hasvarious interior wall structures 135. The interior wall structuresreinforce the outer wall 140 of the housing portion 125 and support andlongitudinally separate various components of the rotation mechanism 90,the catheter shaft 106, and the torque portion 130. The housing portion125 may be made of materials such as, for example, polymers, metals,and/or etc.

As indicated in FIG. 3, the catheter shaft 106 is secured to the distalregion of the housing portion 125. The torque portion 130 has structuralfeatures, such as, for example, one or more circumferential grooves 145,that interface with some of the interior wall structures 135 to preventthe torque portion 130 from proximal-distal displacement relative to thehousing portion 125 while supporting the torque portion 130 in rotatingdisplacement relative to the housing portion 130, the rotation beingabout a common longitudinal axis of the housing portion and torqueportion.

As can be understood from FIG. 3, the linear member 120 extends from adistal end of the rotation mechanism 90, through the interior of thehousing portion 125, and through the catheter shaft 106. The proximalend of the linear member 120 is coupled to the distal end of therotation mechanism 90 such that rotation of the rotation mechanism 90causes the linear member 120 to similarly rotate within the confines ofthe housing portion 125 and the catheter shaft 106 about a longitudinalaxis of the linear member 120. Thus, as can be understood from FIGS.1-3, rotation of the torque portion 130 clockwise causes the linearmember 120 to rotate clockwise, thereby causing the leadless pacemaker102 at the distal end of the delivery system 100 to rotate clockwiseabout the longitudinal axis of the leadless pacemaker 102. Thisclockwise rotation will cause the helical anchor at the distal end ofthe leadless pacemaker to screw into the cardiac tissue to attach theleadless pacemaker to the cardiac tissue.

Oppositely, rotation of the torque portion 130 counter-clockwise causesthe linear member 120 to rotate counter-clockwise, thereby causing theleadless pacemaker 102 at the distal end of the delivery system 100 torotate counter-clockwise about the longitudinal axis of the leadlesspacemaker 102. This counter-clockwise rotation will cause the helicalanchor at the distal end of the leadless pacemaker to unscrew from thecardiac tissue to detach the leadless pacemaker from the cardiac tissue.

FIG. 4 is an exploded isometric view of the handle 108 and the rotationmechanism 90 enclosed therein. As shown in FIG. 4, the rotationmechanism 90 includes a ratchet assembly 150, a distal spring 155, ashuttle 160, a proximal spring 165, a stop ring 170 and a drive shaft175 of the torque portion 130. These components of the rotationmechanism 90 are enclosed by the housing portion 125. The drive shaft175 of the torque portion 130 distally extends from a grip 180 of thetorque portion 130.

FIG. 5 is a longitudinal cross section of the handle 108 and rotationmechanism enclosed therein as viewed along section line 5-5 in FIG. 2.As can be understood from FIGS. 2-5, the drive shaft 175 distallyextends from the grip 180 of the torque portion 130 into the housingportion 125 to be supported in a rotating fashion by various interiorwall structures 135 of the housing portion 125. The drive shaft 175extends through the other components of the drive mechanism 90,specifically, the ratchet assembly 150, the distal spring 155, theshuttle 160, the proximal spring 165, and the stop ring 170.

As depicted in FIG. 6, which is an isometric view of the torque portion130 of the handle 108, the drive shaft 175 has a generally cylindricalouter surface that is interrupted by flanges and recesses that definecircumferential grooves 145 that interface with the interior wallstructures 135 of the housing portion 125 to act as rotational bearingsurfaces for the drive shaft and prevent distal-proximal displacement ofthe drive shaft relative to the housing 125. A helical partial thread185 radially projects from the cylindrical outer surface of the driveshaft 175 near the midpoint of the length of the drive shaft 175. Thishelical partial tread 185 threadably engages threads 250 on the threadedcylindrical interior or axial shaft 235 of the shuttle 160 as discussedbelow. The torque portion 130 may be made of materials such as, forexample, polymers, metals, and/or etc.

As indicated in FIGS. 7A and 7B, which are opposite isometric views ofthe ratchet assembly 150 of the rotation mechanism 90, the ratchetassembly 150 includes an inner notched-rim wheel 190 and an outer dualpawl 195 that includes opposed tab arms 197 that engage notches orrecesses 200 defined in the outer circumferential surface of a rim 205of the inner notched-rim wheel 190. A circumferentially extending keyridge 210 and a longitudinally extending key ridge 215 project radiallyinward from an inner circumferential surface of a cylinder portion 220of the inner notched-rim wheel 190.

As can be understood from FIGS. 3-7B, the ratchet assembly 150 extendsabout the circumference of the distal end of the drive shaft 175. Thekey ridges 210, 215 of the inner notched-rim wheel 190 are received in amating interference fit with complementary female circumferential andlongitudinal slots 145, 225 defined in the drive shaft 175 near itsdistal end. On account of this arrangement, clockwise orcounter-clockwise rotation of the drive shaft 175 rotates the innernotched-rim wheel 190 in the same directions. Rotational displacement ofthe inner notched-rim wheel 190 causes the recesses 200 to displaceagainst the pawl arms 195, thereby creating a tactile sensation in thegrip 180 of the torque portion 130 when the torque portion is rotatedrelative to the housing 125. The inner notched-rim wheel 190 may be madeof materials such as, for example, polymers or etc. The outer dual pawl195 may be made of materials such as, without limitation, engineeringpolymers, and/or metals.

FIGS. 8A and 8B are opposite isometric views of a shuttle 160 of therotation mechanism 90. As reflected in FIGS. 8A and 8B, the shuttle 160includes a cylindrical body 230 with a threaded cylindrical axial shaft235 extending distal-proximal through the body 230, a pair of guidemembers 240 radially projecting outward from the outer circumferentialsurface of the body 230 on opposite sides of the body from each other,and pairs of longitudinally spaced apart ribs 245 radially projectingoutward from the outer circumferential surface of the body 230 andextending circumferentially about the body. The shuttle 160 may be madeof materials such as, without limitation, engineering polymers, and/ormetals.

The thread 250 in the threaded cylindrical axial shaft 235 is amulti-start thread with two, three, four or more thread-start locations255 intersecting the proximal rim 260 and the distal rim 265 of thethreaded cylindrical axial shaft 235. These thread-start locations 255allow the helical partial tread 185 on the drive shaft 175 to enter thethread 250 at multiple locations about the circumference of the proximaland distal rims 260, 265 and threadably engage the thread 250 on thethreaded cylindrical interior or axial shaft 235 of the shuttle 160, ascan be understood from FIGS. 3-5 and as discussed below.

As can be understood from FIGS. 2-5, the pair of guide members 240 arereceived in respective longitudinally extending guide slots 270 definedin the exterior wall 140 of the housing 125 such that the guide members240 linearly displace distal-proximal along the respective guide slots270 as the drive shaft 175 threadably drives the shuttle 160distal-proximal along the length of the drive shaft 160 when the driveshaft is rotated clockwise or counter-clockwise. In some embodiments,the guide slots 270 are in the form of windows daylighting through thewall 140 of the housing 125 such that the displacement of the guidemembers 240 of the shuttle can be visually observed.

FIGS. 9A and 9B are opposite isometric views of a stop ring 170 of therotation assembly 90. As indicated in FIGS. 9A and 9B, the stop ring 170includes a ring 275, a pair of lever arms 280 radially outwardlyprojecting from opposite sides of the ring 275, and a pair of hard stopmembers 285 distally projecting from a distal edge of the ring 275 andat opposite locations on the ring 275. The stop ring 170 may be made ofmaterials such as, for example, polymers, metals, and/or etc.

As illustrated in FIGS. 2, 3 and 5, the stop ring 170 extends around theproximal region of the drive shaft 175, the hard stop members 285extending distally along the drive shaft and generally parallel to thedrive shaft 175. The lever arms 280 radially project outwardly through arespective pair of circumferentially extending window slots 290 definedin the exterior wall 140 of the housing 125.

As can be understood from FIGS. 3, 5, 7A, 7B, 8A and 8B, the distalspring 155 is located between the proximal face of the rim 205 of theinner notched-rim wheel 190 and the distal faces of the guide members240 and the distal pair of ribs 245 of the shuttle 160. When the shuttle160 is fully distally displaced along the length of the drive shaft 175,as depicted in FIGS. 3, 5, 10A and 10B, the distal spring 155 extendsaround the outer cylindrical surface of the cylinder portion 220 of theinner notched-rim wheel 190, the outer cylindrical surface of the driveshaft 175, and the outer cylindrical surface of the shuttle body 230distal the guide members 240.

As can be understood from FIGS. 3, 5, 7A, 7B, 8A and 8B, the proximalspring 165 is located between the distal face of the ring 275 of thestop ring 170 and the proximal faces of the guide members 240 and theproximal pair of ribs 245 of the shuttle 160. When the shuttle 160 isfully proximally displaced along the length of the drive shaft 175, asdepicted in FIGS. 11A and 11B, the proximal spring 165 extends aroundthe outer cylindrical surface of the drive shaft 175 and the outercylindrical surface of the shuttle body 230 proximal the guide members240. The proximal spring 165 will also be located radially inward of thehard stop members 285.

The springs 155, 165 may be made of materials such as, for example,metals, compressible polymers, and/or etc. While depicted as beinghelical springs in the various FIGS. herein, in other embodiments, thesprings 155, 165 may have other configurations such as, for example,elastomeric polymers, or may even be replaced with other biasing memberssuch as, for example, bands that stretch and create tension on theshuttle.

As can be understood from FIGS. 3 and 5, in some embodiments, the distaland proximal springs 155, 165 may abut against the respective proximaland distal faces of the guide members 240 and ribs 245. In otherembodiments, as indicated in FIGS. 10A-11B, rings 295 extend about theouter cylindrical surfaces of the shuttle body 230 proximal and distalthe guide members 240 and ribs 245. These rings 295 may be formed ofmaterials such as, without limitation, engineering polymers, and/ormetals and will contact the respective springs 155, 165.

FIG. 10A is an isometric view of the handle 108 with a portion of ahousing 125 removed to reveal the rotation mechanism 90 enclosedtherein, the shuttle 160 being in a most distal location along a shaft175 of the torque portion 130 of the handle. FIG. 10B is a longitudinalcross-section of the rotation mechanism 90 in the region identified inFIG. 10A and as taken along section line 10B-10B in FIG. 10A.

As illustrated in FIGS. 10A and 10B, when the shuttle 160 is in the mostdistal location along the shaft 175 of the torque portion 130 of thehandle 108, the distal spring 155 is compressed between the distal ring295 of the shuttle 160 and an interior wall 135 immediately proximal theratchet assembly 150. As can be understood from FIG. 10A, on account ofthe pitch direction of the helical partial thread 185 on the shaft 175of the torque portion 130, and despite the distal spring 155 biasing theshuttle proximally such that its distal rim 265 (see FIGS. 8A and 8B) iskept in abutting contact with the thread 185, the thread 185 of theshaft 175 does not engage the interior threads 250 of the shuttle 160 aslong as the torque portion 130 is rotated counter-clockwise (CCW), thethread 185 simply riding along the distal rim 265 of the shuttle 160.Thus, the torque portion 130 and the linear member 120 extendingdistally therefrom, as shown in FIG. 3, can infinitely rotate CCW andcause the leadless pacemaker 102 to rotate CCW, as can be understoodfrom FIG. 1, such that the helical anchor on the distal end of theleadless pacemaker will unscrew from cardiac tissue in which it may beimbedded. The CCW rotation causes the ratchet assembly 150 to generatean incremental/stepped tactile sensation in the grip 180 of the torqueportion 130 of the handle 108.

Conversely and as can be understood from FIG. 10A, on account of thepitch direction of the helical partial thread 185 on the shaft 175 ofthe torque portion 130, and because the distal spring 155 biases theshuttle proximally such that its proximal rim 265 is kept in abuttingcontact with the thread 185, the thread 185 of the shaft 175 engages theinterior threads 250 of the shuttle 160 once the torque portion 130 isrotated clockwise (CW) and the shaft thread 185 encounters one of themultiple thread-start locations 255 intersecting the proximal rim 265.Once threaded engagement occurs between the shaft thread 185 and theshuttle threads 250, further CW rotation of the torque portion 130 willcause the shuttle 160 to proximally displace along the shaft 175. As canbe understood from FIGS. 1 and 3, the CW rotation of the torque portion130 and the linear member 120 extending distally therefrom rotates theleadless pacemaker 102 CW such that the helical anchor on the distal endof the leadless pacemaker will screw into cardiac tissue contacting thehelical anchor. The CW rotation causes the ratchet assembly 150 togenerate an incremental/stepped tactile sensation in the grip 180 of thetorque portion 130 of the handle 108.

Continued CW rotation of the torque portion 130 further proximallydisplaces the shuttle 160 along the shaft 175 as the shuttle threads 250move proximally along the rotating shaft thread 185, which is confinedto rotation about the longitudinal axis of the shaft and does notdisplace distal-proximal. As the shuttle moves along the shaft, theshuttle guide members 240 linearly displace proximally along therespective guide slots 270, and this displacement can be observedthrough the windows created by the guide slots 270 in the exterior wall140 of the housing 125, as can be understood from FIGS. 2, 4 and 5.

As the CW rotation of the torque portion 130 causes the shuttle 160 todisplace proximally from the most distal location, as depicted in FIGS.10A and 10B, the tactile sensation and resistance felt in the grip 180of the torque portion 130 will remain constant as provided by theratchet assembly 150 until the shuttle 160 is sufficiently proximallydisplaced such that the proximal faces of the shuttle guide members 240come into abutting contact with the distal tip faces of the hard stopmembers 285 of the stop ring 170, as illustrated in FIGS. 11A and 11B.In some embodiments, the rotational resistance may increase slightly asthe proximal spring 165 is initially contacted by the shuttle proximalring 295 immediately prior to the abutting contact between the shuttleguide members 240 and the hard stop members 285, thereby placing theproximal spring 165 in the initial stages of compression between theshuttle proximal ring 295 and the distal face of the ring 275 of thestop ring 170.

In one embodiment, the number of CW rotations needed to displace theshuttle from the most distal position depicted in FIGS. 10A and 10B tothe stopped position shown in FIGS. 11A and 11B will be two andone-quarter rotations of the grip 180 of the torque portion 130 of thehandle 108. This two and one-quarter rotations is based on what isconsidered to be a typical number of turns of the helical anchor of theleadless pacemaker to cause the helical anchor to fully imbed in thecardiac tissue without over-penetrating the cardiac tissue. In otherembodiments, the number of rotations required to displace the shuttlebetween the locations depicted in FIGS. 10A-10B and 11A-11B will be moreor less than two and one-quarter rotations.

Once the proximal faces of the shuttle guide members 240 come intoabutting contact with the distal tip faces of the hard stop members 285of the stop ring 170, as illustrated in FIGS. 11A and 11B, this contactwill notify the physician that the prescribed number of rotations of thehelical anchor of the leadless pacemaker has been reached. At thispoint, should the physician decide additional CW rotations of thehelical anchor of the leadless pacemaker are necessary to achieve adesired level of fixation to the cardiac tissue, as illustrated in FIGS.12A and 12B, the lever arms 280 of the stop ring 170 may be rotatedabout the longitudinal axis of the shaft 175 to cause the hard stopmembers 285 to move out of the way of the shuttle guide members 240 suchthat continued CW rotations of the grip 180 of the torque portion 130 ofthe handle 108 will continue to proximally displace the shuttle 160.

As indicated in FIGS. 12A and 12B, sufficient CW rotations of the grip180 of the torque portion 130 of the handle 108 will cause the shuttle160 to fully compress the proximal spring 165 and the shuttle 160 tomove proximally past the shaft thread 185 such that the shaft thread 185no longer is in threaded engagement with the shuttle threads 250 but isdistal the shuttle threads 250. At this point, the grip 180 of thetorque portion 130 of the handle 108 can be rotated infinitely CW as theshaft thread 185 simply rides along the proximal edge 260 of the shuttle160 on account of the pitch direction of the shaft helical partialthread 185. Thus, the torque portion 130 and the linear member 120extending distally therefrom, as shown in FIG. 3, can infinitely rotateCW and cause the leadless pacemaker 102 to rotate CW, as can beunderstood from FIG. 1, such that the helical anchor on the distal endof the leadless pacemaker will screw into cardiac tissue for fixationthereto.

Conversely and as can be understood from FIG. 12B, on account of thepitch direction of the helical partial thread 185 on the shaft 175 ofthe torque portion 130, and because the proximal spring 165 biases theshuttle distally such that its distal proximal rim 260 is kept inabutting contact with the thread 185, the thread 185 of the shaft 175engages the interior threads 250 of the shuttle 160 once the torqueportion 130 is rotated counter-clockwise (CCW) and the shaft thread 185encounters one of the multiple thread-start locations 255 intersectingthe distal rim 260. Once threaded engagement occurs between the shaftthread 185 and the shuttle threads 250, further CCW rotation of thetorque portion 130 will cause the shuttle 160 to distally displace alongthe shaft 175. This distal displacement of the shuttle will continueuntil it reaches the most distal location on the shaft, as indicated inFIGS. 10A and 10B, or the grip 180 of the torque portion 130 is againrotated CW. In either case, the CCW rotation of the grip 180 will bringabout CCW rotation of the helical anchor for unscrewing from cardiactissue, and CW rotation of the grip 180 will bring about CW rotation ofthe helical anchor for screwing into cardiac tissue.

In the event the grip 180 is again rotated CW to bring about screwing ofthe helical anchor into the cardiac tissue, to again allow for theadvantages of the rotation limit warning afforded by the stop ring 170,the stop ring 170 can be reset (rotated) such that its hard stop members285 are again aligned with the shuttle guide members 240 to come intoabutting contact with the distal tip faces of the of the stop ring 170,as can be understood from FIGS. 10A-11B.

The warning aspect of the rotation mechanism 90 of FIGS. 2-12B could beadapted to provide multiple warnings to the physician when a certainnumber of rotations of the leadless pacemaker has occurred. Forinstance, as illustrated in FIG. 9C, which is a side plan view of amodification to the stop ring 170 of FIGS. 9A and 9B, a warning could beprovided every full rotation of the torque portion 130 of the handle 108to alert the physician of another complete rotation of the leadlesspacemaker. This could be achieved, for example, by providing hard stopmembers 285 that have a stepped configuration with a series of steps287A-D that are radially offset from each other and increasinglyproximally located. Each step 287A-D provides an increasingly proximalpoint of contact with the shuttle guide members 240. Thus, once theshuttle guide members 240 have contacted a first pair of steps 287A ofthe hard stop members 285 and the physician desires to make anadditional rotation of the leadless pacemaker, the stop ring 170 can beincrementally rotated to align the shuttle guide members 240 with thenext radially adjacent pair of steps 287B, this next radially adjacentpair of steps 287B being located more proximally than the initiallycontacted pair of steps 287A. The physician can then rotate the leadlesspacemaker a full turn before contacting the second pair of steps 287B.The process can then be repeated for successive contacts with the restof the steps 287C and 287D for two more purposeful and incrementalrotations of the leadless pacemaker.

The warning mechanism afforded by the embodiment of FIGS. 2-12B providesa hard stop at a certain rotation level in the torque portion of thehandle. It eliminates any chance of the physician by-passing a morepassive indicator by requiring an extra motion to continue rotating,guaranteeing that the physician will notice the warning by completelypreventing further rotations until actively addressing the hard stop.Specifically, it requires another user action in order to continuerotating the torque portion of the handle and, by extension, theleadless pacemaker. A visual indicator on the outside of the handlepresents that the warning system has been contacted.

C. Handle with Rotation Mechanism Employing O-Ring Rotation LimitWarning

To begin a discussion of another embodiment of the rotation mechanism 90of the handle 108 of the leadless pacemaker delivery system of FIG. 1,reference is now made to FIGS. 13 and 14. FIG. 13 is an isometric viewof the handle 108 with a portion of a housing 125 of the handle 108removed to reveal the alternative rotation mechanism 90 enclosedtherein, and FIG. 14 is a longitudinal cross section of the handle 108and alternative rotation mechanism 90 enclosed therein as viewed alongsection line 13-13 in FIG. 13.

As can be understood from a comparison of FIGS. 13 and 14 to FIGS. 3-5,the alternative version of the rotation mechanism 90 and the surroundingelements of the handle 108 and leadless pacemaker delivery system of theversion of FIGS. 13 and 14 share the majority of elements and operationas discussed above with respect to FIGS. 1-12B, except an O-ring 300 hasreplaced the stop ring 170 and the shuttle 160 employs features thatinteract with the O-ring 300. Accordingly, the preceding discussion ofFIGS. 1-12B is equally applicable to the version of the rotationmechanism 90 and surrounding elements of the handle 108 shown in FIGS.13 and 14, except as will now be specifically discussed with respect toFIGS. 13-18B.

As indicated in FIGS. 13 and 14, the O-ring 300 extendscircumferentially around, and is coaxial with, the shaft 175 of thetorque portion 130. Also, the O-ring 300 is sandwiched between paralleland spaced-apart flange rings 305 of the shaft 175 and extend radiallyoutwardly from the outer circumference of the shaft 175. The O-ring 300and flange rings 305 are located near the proximal end of the shaft 175of the torque portion 130. The O-ring 300 may be made of materials suchas, for example, elastomeric polymer and have a durometer of betweenapproximately 10 and approximately 100 Shore A. The O-ring 300, which iscompressible, may have a circular transverse cross-section as shown inFIG. 15B. Alternatively, the O-ring 300 may have a transversecross-section that is oval, square, rectangular, or etc.

As shown in FIG. 14, the shuttle 160 includes a proximal innercircumferential chamber 310 at the proximal end of the shuttle and adistal inner circumferential chamber 315 at the distal end of theshuttle. Each chamber 310, 315 includes a pair of spaced-apart radiallyinwardly extending lips, these lips being an outer lip and an inner lip.Specifically, for the proximal chamber 310, the outer lip is a proximalouter lip 320 at the proximal edge of the shuttle 160, and the inner lipis a distal inner lip 325 distal the proximal outer lip 320. The lips320, 325 are spaced-apart from each other and radially inwardly projectfrom an inner cylindrical surface 327 of the proximal chamber 310. Forthe distal chamber 315, the outer lip is a distal outer lip 330 at thedistal edge of the shuttle 160, and the inner lip is a proximal innerlip 335 proximal the distal outer lip 330. The lips 330, 335 arespaced-apart from each other and radially inwardly project from an innercylindrical surface 337 of the distal chamber 315.

FIG. 15A is an isometric view of the handle 108 with a portion of ahousing 125 removed to reveal the rotation mechanism 90 enclosedtherein, the shuttle 160 being in a most distal location along a shaft175 of the torque portion 130 of the handle and the springs 155, 165being hidden for clarity purposes. FIG. 15B is a longitudinalcross-section of the rotation mechanism 90 in the region identified inFIG. 15A and as taken along section line 15B-15B in FIG. 15A.

As illustrated in FIGS. 15A and 15B, when the shuttle 160 is in the mostdistal location along the shaft 175 of the torque portion 130 of thehandle 108, the distal spring 155 (shown in FIGS. 13 and 14) iscompressed between the distal ring 295 of the shuttle 160 and aninterior wall 135 immediately proximal the ratchet assembly 150. As canbe understood from FIG. 15A, on account of the pitch direction of thehelical partial thread 185 on the shaft 175 of the torque portion 130,and despite the distal spring 155 biasing the shuttle proximally suchthat its distal rim 265 is kept in abutting contact with the thread 185,the thread 185 of the shaft 175 does not engage the interior threads 250of the shuttle 160 as long as the torque portion 130 is rotatedcounter-clockwise (CCW), the thread 185 simply riding along the distalrim 265 of the shuttle 160. Thus, the torque portion 130 and the linearmember 120 extending distally therefrom, as shown in FIG. 13, caninfinitely rotate CCW and cause the leadless pacemaker 102 to rotateCCW, as can be understood from FIG. 1, such that the helical anchor onthe distal end of the leadless pacemaker will unscrew from cardiactissue in which it may be imbedded. The CCW rotation causes the ratchetassembly 150 to generate an incremental/stepped tactile sensation in thegrip 180 of the torque portion 130 of the handle 108.

Conversely and as can be understood from FIG. 15A, on account of thepitch direction of the helical partial thread 185 on the shaft 175 ofthe torque portion 130, and because the distal spring 155 (shown inFIGS. 13 and 14) biases the shuttle proximally such that its proximalrim 265 is kept in abutting contact with the thread 185, the thread 185of the shaft 175 engages the interior threads 250 of the shuttle 160once the torque portion 130 is rotated clockwise (CW) and the shaftthread 185 encounters one of the multiple thread-start locations 255intersecting the proximal rim 265. Once threaded engagement occursbetween the shaft thread 185 and the shuttle threads 250, further CWrotation of the torque portion 130 will cause the shuttle 160 toproximally displace along the shaft 175. As can be understood from FIGS.1 and 13, the CW rotation of the torque portion 130 and the linearmember 120 extending distally therefrom rotates the leadless pacemaker102 CW such that the helical anchor on the distal end of the leadlesspacemaker will screw into cardiac tissue contacting the helical anchor.The CW rotation causes the ratchet assembly 150 to generate anincremental/stepped tactile sensation in the grip 180 of the torqueportion 130 of the handle 108.

Continued CW rotation of the torque portion 130 further proximallydisplaces the shuttle 160 along the shaft 175 as the shuttle threads 250move proximally along the rotating shaft thread 185, which is confinedto rotation about the longitudinal axis of the shaft and does notdisplace distal-proximal. As the shuttle moves along the shaft, theshuttle guide members 240 linearly displace proximally along therespective guide slots 270. In some embodiments where the guide slots270 daylight through the exterior wall 140 of the housing 125, thedisplacement of the shuttle guide members 240 can be observed throughthe windows created by the guide slots 270 in the exterior wall 140 ofthe housing 125, similar to that discussed above with respect to FIGS.2, 4 and 5.

As the CW rotation of the torque portion 130 causes the shuttle 160 todisplace proximally from the most distal location, as depicted in FIGS.15A and 15B, the tactile sensation and resistance felt in the grip 180of the torque portion 130 will remain constant as provided by theratchet assembly 150 until the shuttle 160 is sufficiently proximallydisplaced such that the proximal boundary of the proximal outer lip 320,which is at the shuttle proximal edge 260, encounters the distalboundary of the O-ring 300, as illustrated in FIGS. 16A and 16B. At thistime, the resistance felt in the grip 180 of the torque portion 130 willbegin to gradually increase as the radially inwardly projecting lip 320begins to compress the O-ring 300 as the lip 320 is caused toincreasingly move proximally over the O-ring 300. In some embodiments,the rotational resistance may also increase slightly as the proximalspring 165 (shown in FIGS. 13 and 14) is initially contacted by theshuttle proximal ring 295 immediately prior to the radially inwardlyprojecting lip 320 begins to encounter and radially inwardly compressthe O-ring 300, thereby placing the proximal spring 165 in the initialstages of compression between the shuttle proximal ring 295 and aninterior wall 135 of the housing 125.

In some embodiments, the shuttle may be able to expand to clear theO-ring or a similar structural impediment to the proximal displacementof the shuttle along the shaft. This expansion capability of the shuttlemay be in place of the O-ring compressing or in addition to the O-ringcompressing.

In one embodiment, the number of CW rotations needed to displace theshuttle from the most distal position depicted in FIGS. 15A and 15B tothe stopped position shown in FIGS. 16A and 16B will be two andone-quarter rotations of the grip 180 of the torque portion 130 of thehandle 108. This two and one-quarter rotations is based on what isconsidered to be a typical number of turns of the helical anchor of theleadless pacemaker to cause the helical anchor to fully imbed in thecardiac tissue without over-penetrating the cardiac tissue. In otherembodiments, the number of rotations required to displace the shuttlebetween the locations depicted in FIGS. 15A-15B and 16A-16B will be moreor less than two and one-quarter rotations.

Once the proximal boundary of the proximal outer lip 320, which is atthe shuttle proximal edge 260, encounters the distal boundary of theO-ring 300, as illustrated in FIGS. 16A and 16B, this contact willnotify the physician that the prescribed number of rotations of thehelical anchor of the leadless pacemaker has been reached. At thispoint, should the physician decide additional CW rotations of thehelical anchor of the leadless pacemaker are necessary to achieve adesired level of fixation to the cardiac tissue, as can be understoodfrom FIGS. 16A-17B, continued CW rotations of the grip 180 of the torqueportion 130 of the handle 108 will continue to proximally displace theshuttle 160 and drive the radially inwardly projecting lip 320 at theshuttle proximal edge 260 completely over and proximally past the O-ring300 such that the O-ring 300 is received in the proximal innercircumferential chamber 310 as indicated in FIGS. 17A and 17B.

Since the O-ring 300 is confined distally and proximally by flange rings305 of the shaft 175, when the lip 320 is caused to pass over the O-ring300, the O-ring is compressed such that it is deflected into anelliptical cross-section from its self-biasing, or non-deflected,circular cross-section. This change in cross-section of the O-ring 300increases resistance to the rotation of the torque portion 130 of thehandle 108, thereby notifying the physician that the prescribed numberof rotations of the helical anchor of the leadless pacemaker has beenreached.

As indicated in FIGS. 18A and 18B, sufficient CW rotations of the grip180 of the torque portion 130 of the handle 108 will cause the shuttle160 to fully compress the proximal spring 165 (shown in FIGS. 13 and 14)and the shuttle 160 to move proximally past the shaft thread 185 suchthat the shaft thread 185 no longer is in threaded engagement with theshuttle threads 250 but is distal the shuttle threads 250. At thispoint, the grip 180 of the torque portion 130 of the handle 108 can berotated infinitely CW as the shaft thread 185 simply rides along theproximal edge 260 of the shuttle 160 on account of the pitch directionof the shaft helical partial thread 185. Thus, the torque portion 130and the linear member 120 extending distally therefrom, as shown in FIG.13, can infinitely rotate CW and cause the leadless pacemaker 102 torotate CW, as can be understood from FIG. 1, such that the helicalanchor on the distal end of the leadless pacemaker will screw intocardiac tissue for fixation thereto.

Conversely and as can be understood from FIG. 18B, on account of thepitch direction of the helical partial thread 185 on the shaft 175 ofthe torque portion 130, and because the proximal spring 165 biases theshuttle distally such that its distal proximal rim 260 is kept inabutting contact with the thread 185, the thread 185 of the shaft 175engages the interior threads 250 of the shuttle 160 once the torqueportion 130 is rotated counter-clockwise (CCW) and the shaft thread 185encounters one of the multiple thread-start locations 255 intersectingthe distal rim 260. Once threaded engagement occurs between the shaftthread 185 and the shuttle threads 250, further CCW rotation of thetorque portion 130 will cause the shuttle 160 to distally displace alongthe shaft 175. This distal displacement of the shuttle will cause thelip 320 to displace distally over the O-ring 300 such that the lip 320is once again distal the O-ring 300 and outside the proximal chamber310, as shown in FIGS. 16A and 16B. Further CCW rotation of the torqueportion 130 further drives the shuttle 160 distally until it reaches themost distal location on the shaft, as indicated in FIGS. 15A and 15B, orthe grip 180 of the torque portion 130 is again rotated CW. In eithercase, the CCW rotation of the grip 180 will bring about CCW rotation ofthe helical anchor for unscrewing from cardiac tissue, and CW rotationof the grip 180 will bring about CW rotation of the helical anchor forscrewing into cardiac tissue.

As can be understood from FIGS. 17A-18B, the proximal-distal width ofthe inner cylindrical surface 327 of the proximal chamber 310 providesproximal-distal space for the O-ring 300 reside to allow the distalspring 165 (see FIGS. 13 and 14) to reengage the shaft helical partialthread 185 with the shuttle inner thread 250 via one of the thread-startlocations 255 inward of the distal rim 265 of the shuttle 160.

In the event the grip 180 is again rotated CW to bring about screwing ofthe helical anchor into the cardiac tissue, the embodiment of FIGS.13-18B is advantageous in that there is nothing to “reset” to againallow for the advantages of the rotation limit warning afforded by theO-ring 300. Specifically, the resilience of the O-ring 300 and the lip320 being positioned distal the O-ring 300 is sufficient to again availthe rotation mechanism 90 of the operational benefits of the rotationlimit warning of the O-ring 300.

The warning aspect of the rotation mechanism 90 of FIGS. 13-18B could beadapted to provide multiple warnings to the physician when a certainnumber of rotations of the leadless pacemaker has occurred. Forinstance, additional O-rings 300 could be incrementally located alongthe shaft 175 proximal from a first O-ring 300 such that a purposefulincrease in effort must be undertaken by the physician each time thephysician desires to proceed with another rotation of the leadlesspacemaker.

This O-ring embodiment of FIGS. 13-18B has a number of advantages. Forexample, the O-ring embodiment provides tactile feedback at a certainrotation level in the handle. The O-ring embodiment may be adjustablefor different levels of physician effort to over-come the warningmechanism; for example, by modifying the O-ring size and durometer orchanging the interference level on the shuttle.

The O-ring embodiment allows a physician to maintain focus on anyfluoroscopy or information screens in the operating room. Also, no extramotion is required by the physician to over-come warning system. TheO-ring embodiment informs the physician during initial implant as wellas during a re-positioning of the leadless pacemaker. The warningmechanism of the O-ring embodiment may be completely hidden within theconfines of the handle. Finally, the handle is omni-directional in thatit does not need to be oriented in a specific fashion to go past thewarning mechanism.

D. Handle with Rotation Mechanism Employing Handle Bump Limit Warning

To begin a discussion of yet another version of the rotation mechanism90 of the handle 108 of the leadless pacemaker delivery system of FIG.1, reference is now made to FIG. 19, which is an isometric view of halfof the shuttle 160 employed in this third version of the rotationmechanism. As shown in FIG. 19 and similar to the shuttle 160 discussedabove with respect to FIGS. 8A and 8B, the shuttle 160 includes acylindrical body 230 with a threaded cylindrical axial shaft 235extending distal-proximal through the body 230, a pair of guide members240 radially projecting outward from the outer circumferential surfaceof the body 230 on opposite sides of the body from each other, and pairsof longitudinally spaced apart ribs 245 radially projecting outward fromthe outer circumferential surface of the body 230 and extendingcircumferentially about the body. A rounded bump or ridge 400 is locatedon the lateral sides of each guide member 240. All other aspects of theshuttle 160 are as discussed above with respect to FIGS. 8A and 8B.

FIG. 20 is an isometric view of a half of a proximal end of the housing125 that is immediately adjacent the torque portion 130 of the handle108, as can be understood by comparison to FIG. 4. FIG. 21 is a planview of the half of the housing 125. As can be understood from FIGS. 20and 21 and similar to the discussion above with respect to FIGS. 3-5,the housing 125 includes the interior and exterior walls 135, 140 andthe longitudinally extending guide slot 270, which is defined byparallel longitudinally extending rails 405. Just proximal of themidpoint of the slot 270 are opposed rounded bumps 410 projectinginwardly from its associated rail 405.

At this point, it should be noted that other aspects of the handle 108and rotation mechanism 90 of this version of the device aresubstantially similar, if not identical, to those aspects and featuresdescribed herein with respect to other implementations of the presentdisclosure, except that this version does not employ the hard stop 170or the O-ring 300 and its interacting lips 320, 325, chamber 310 andinner circumferential surface 327. Also, the displacement of the shuttle160 along the shaft 175, its incremental tactile sensation via theratchet assembly 150, and its directional biasing via the springs 155,165 all occur as discussed above with respect to FIGS. 1-18B, thedifference of this version versus the previous versions being that therotation limit warning of this third version is facilitate via theinteraction of the rail bumps 410 and the shuttle bumps 400, as will nowbe discussed with respect to FIG. 22.

As can be understood from FIG. 22, which is a bottom plan view of therotation mechanism 90 and housing 125, a guide member 240 is located ina slot 270 between the rails 405, the bumps 400 of the guide member 240projecting towards the rails 405, and the bumps 410 of the rails 405projecting towards the guide member 240. As the shuttle 160 displacesproximally along the shaft 175 via CW rotation of the torque portion130, the bumps 400, 410 contact, and deflect against, each other toprovide a tactile increase in rotational effort at the grip 180 of thetorque portion 130, thereby indicating to the physician that prescribednumber of rotations of the helical anchor of the leadless pacemaker hasbeen reached. At this point, should the physician decide additional CWrotations of the helical anchor of the leadless pacemaker are necessaryto achieve a desired level of fixation to the cardiac tissue, additionalCW rotations may take place. Thus, the operation of the limit warning ofthis third version of the rotation mechanism may be said to operatesimilar to that of the O-ring version discussed above with respect toFIGS. 13-18B, the exception being that the interaction of the O-ring andlips is replace by the interaction of the bumps 400, 410.

The warning aspect of the rotation mechanism 90 of FIGS. 19-22 could beadapted to provide multiple warnings to the physician when a certainnumber of rotations of the leadless pacemaker has occurred. Forinstance, additional pairs of rail bumps 410 could be incrementallylocated along the slot 270 proximal from a first pair of rail bumps 410such that a purposeful increase in effort must be undertaken by thephysician each time the physician desires to proceed with anotherrotation of the leadless pacemaker.

The warning mechanism afforded by the bumps can be adjusted fordifferent levels of physician effort to overcome the warning mechanism;for example, by modifying the level of interference by changing bumpheight and modifying flexural stiffness of shuttle ribs on which thehousing bumps are located. All the bump features can be molded intoplace. The warning mechanism allows the physician to maintain focus onany fluoroscopic or information screens in the operating room, and noextra motion is required by the user to over-come warning system. Thewarning mechanism may inform the physician during initial implant aswell as during a re-positioning. The warning mechanism may be completelyencapsulated inside handle, and the handle may be omni-directional inthat it does not need to be oriented in a specific fashion to go pastthe warning mechanism.

E. Handle with Rotation Mechanism Employing Malleable Thread

To begin a discussion of yet another version of the rotation mechanism90 of the handle 108 of the leadless pacemaker delivery system of FIG.1, reference is now made to FIG. 23, which is a longitudinalcross-section of a rotation mechanism 90 in accordance with thisdisclosure. As shown in FIG. 23 and similar to the shuttle 160 discussedabove with respect to FIGS. 8A and 8B, the shuttle 160 includes acylindrical body 230 with a threaded cylindrical axial shaft 235extending distal-proximal through the body 230 and including one or morethreads 250, a pair of guide members 240 radially projecting outwardfrom the outer circumferential surface of the body 230 on opposite sidesof the body 230 from each other, and pairs of longitudinally spacedapart ribs 245 radially projecting outward from the outercircumferential surface of the body 230 and extending circumferentiallyabout the body. The shuttle 160 of FIG. 23 is sized such that when theshuttle 160 is in a proximal position, at least a portion of the threads250 engage a helical partial thread 180 of a torque portion 130 of ahandle 108. Generally, the proximal position of the shuttle 160 is aposition in which further proximal translation of the shuttle 160 isprevented by another structure or component of the rotation mechanism90. For example, in certain implementations, the proximal position maycorrespond to a maximum proximal position at which the shuttle 160 abutsa proximal interior wall of the handle 108 (such as the interior wall135 shown in FIG. 18B) or is prevented from additional proximaltranslation by a compressed spring, bumper, or similar resilientstructure disposed between the shuttle 160 and a proximal interior wallof the handle 108. As illustrated in FIG. 23, the proximal position mayalso correspond to one or more positions of the shuttle 160 at which theshuttle 160 is prevented from additional proximal translation by a stopring 170 having one or more distinct stops (as previously discussed inthe context of FIGS. 2-12B). At this point, it should be noted thatother aspects of the handle 108 and rotation mechanism 90 of thisversion of the device are substantially similar, if not identical, tothose aspects and features described herein with respect to the otherversions of the present disclosure, except in this version the shuttle160 is sized such that at least a portion of the threads 250 of theshuttle 160 engage the partial helical partial thread 185 of the handle108 when the shuttle 160 is in a proximal position.

In rotation mechanisms according to this version of the rotationmechanism, tactile feedback is provided by threads adapted to deform orfail when sufficient torque is applied to the torque portion 130 of thehandle 108 after the shuttle 160 has reached a proximal position. Morespecifically, when the shuttle 160 reaches the proximal position byrotation of the torque portion 130, additional translation of theshuttle 160 is prevented by features of the rotation mechanism 90, suchas the stop ring 170, or, in other implementations a spring (such as thespring 165 shown in FIG. 14), an interior wall of the handle 108 (suchas the interior wall 135 shown in FIG. 18B), a bumper (such as theelastomeric bumpers 490, 495 shown in FIG. 25), or any similar structuredisposed between the handle 108 that prevents proximal translation ofthe shuttle 160.

When the shuttle 160 is in the proximal position (as shown in FIG. 23),additional torque applied to the torque portion 130 results in stressapplied to a portion of the threads 250 of the shuttle 160 and thepartial helical partial thread 185 of the handle 108. If the torqueapplied is sufficiently high, one or both of the threads 250 and thepartial helical partial thread 185 may deform and/or fail. When suchdeformation or failure occurs, the threads 250 and the partial helicalthread 285 may disengage and, as a result, the torque portion 130 mayfreely rotate within the housing 180.

In light of the foregoing, the rotation mechanism 90 illustrated in FIG.23 provides tactile feedback and warning by resisting rotation of thetorque portion 130 when the shuttle 160 reaches the proximal position.More specifically, as the shuttle 160 translates towards the proximalposition, rotation of the torque portion 130 is opposed by a rotationalresistance which may be attributable to friction of components of therotation mechanism 90 or other features, such as springs, that may bedisposed proximal the shuttle 160. When the shuttle 160 reaches theproximal position, the shuttle 160 is generally prevented from furthertranslation in the proximal direction and, as a result, a warning in theform of substantially increased rotational resistance occurs. In certainimplementations, the rotation mechanism 90 may be configured totranslate the shuttle 160 from a distal position to the proximalposition in a predetermined number of rotations of the torque portion130, such as two and one quarter rotations.

When the shuttle 160 reaches the proximal position, a user may continueto rotate the torque portion 130 to cause further rotation of theleadless pacemaker coupled to the handle 108. However, because theshuttle 160 is substantially prevented from further advancement, suchadditional rotation causes stress on the threads 250 of the shuttle 160and the partial helical thread portion 185 of the torque portion 130and, as a result, increases resistance to rotation of the torque portion130. In certain implementations, further rotation of the torque portion130 may result in reversible elastic deformation of one or both of thethreads 250 and the helical thread portion 185. If the number ofadditional rotations results in sufficient stress, one or both of thethreads 250 and the helical thread portion 185 may plastically deform orotherwise fail. In cases of brittle failure of one or both of thethreads 250 and the helical partial thread 185, a substantial reductionin resistance to rotation of the torque portion 130 may occur. In casesof ductile failure, the tactile feedback may be felt by a user as agradual decrease in resistance to rotation of the torque portion 130. Ineither case, when sufficient failure has occurred, resistance torotation of the torque portion 130 may be reduced to a nominal level asthe threads 250 and the partial helical partial thread 185 (to theextent either remains after the failure) will be substantiallydisengaged.

The warning aspect of the rotation mechanism 90 of FIG. 23 may beadapted to provide controlled failure of either the threads 250 or thepartial helical partial thread 185 in response to a particular torqueapplied using the torque portion 130. By varying the structure,material, shape, or other aspects of the portion of the threads 250 orthe partial helical partial thread 185, failure and, as a result,feedback provided in conjunction with such failure may be controlled.For example, one or both of the materials of the thread 250 and thepartial helical partial thread 185 may be selected to have a specifichardness, elastic modulus, or other material property related tofailure. Alternatively or in addition to specific material selection,the thread 250 or the partial helical partial thread 185 may have apredetermined cross-section, thickness, or shape corresponding to aparticular point of failure. Notably, the parameters used to modify thefailure point of the thread 250 or the partial helical partial thread185 may be applied to the thread 250 or the partial helical partialthread 185 in their entirety or may only correspond to a portionthereof. For example, as shown in FIG. 23, a known portion of the thread250 may engage the partial helical partial thread 185 when the shuttle160 is in the proximal position based on the geometry of components ofthe handle 108. Accordingly, in certain implementations, only the knownportion of the thread 250 may be formed of a particular material or havea particular geometry corresponding to achieve the desired failure pointand rotational resistance profile.

F. Handle with Rotation Mechanism Employing a Bump and Compliant Shuttle

To begin a discussion of another embodiment of the rotation mechanism 90of the handle 108 of the leadless pacemaker delivery system of FIG. 1,reference is now made to FIGS. 24A-26. FIG. 24A is an isometric view ofthe handle 108 with a portion of a housing 125 of the handle 108 removedto reveal the alternative rotation mechanism 90 enclosed therein. FIG.24B is a longitudinal cross-section of the rotation mechanism 90 in theregion identified in FIG. 24A and as taken along section line 24B-24B inFIG. 24A. FIGS. 25 and 26 are additional longitudinal cross-sections ofthe rotation mechanism 90 in the region identified in FIG. 24A.

As can be understood from a comparison of FIG. 24A-26 to FIGS. 1-18B,the alternative version of the rotation mechanism 90 and the surroundingelements of the handle 108 and leadless pacemaker delivery system ofFIGS. 24A-26 share the majority of elements and operation as discussedabove with respect to FIGS. 1-18B. With reference to FIGS. 13-18B, inparticular, however, the O-ring 300 of FIGS. 13-18B and relate retentionstructure has replaced by a bump 500 disposed on the shaft 175 and therings 295 coupled to the shuttle 160 have been replaced by a pair ofgarter springs 502, 504 extending around the shuttle 160. Further, theshuttle 160 is a multi-part shuttle that includes at least two separateshuttle segments 161, 163. The springs 155, 165 have also been omittedfor clarity. Accordingly, the preceding discussion of FIGS. 1-18B isequally applicable to the version of the rotation mechanism 90 andsurrounding elements of the handle 108 shown in FIGS. 24B-26, except aswill now be specifically discussed with respect to FIGS. 24B-26.

As indicated in FIGS. 24A and 24B, the garter springs 502, 504 extendcircumferentially around a distal and proximal end of the shuttle 160and are coaxial with, the shaft 175 of the torque portion 130. Thegarter springs 502, 504 exert an inward force on the shuttle 160 suchthat the shuttle segments 161, 163 are made to abut each other andretain the overall shape of the shuttle 160 in a resting configuration.In certain implementations, the garter springs 502, 504 may be retainedwithin structures of the shuttle 160 such as between parallelcircumferential flanges of the shuttle 160 or within grooves defined inthe outer surface of the shuttle 160. The garter springs 502, 504 may bemade of materials, such as, for example, metals or elastomeric polymers.In certain implementations one or both of the garter springs 502, 504may be replaced by an elastic band or similar compliant member shaped toextend around the shuttle 160. Also, while illustrated in FIGS. 24A-25as including two garter springs 502, 504 additional garter springs (orsimilar compliant) may be included.

As shown in FIG. 24B, the proximal end of the shaft 175 of the torqueportion 130 includes a bump 500 or similar structure extending from theshaft 175. The bump 500 may be integrally formed with the shaft 175 andmay extend around all or part of the circumference of the shaft 175. Thebump 500 may have various shapes and sizes, however, as furtherdiscussed with respect to FIGS. 24B-26, below, the bump 500 generallyextends from the shaft 175 such that as the shuttle 160 translatesproximally along the shaft 175, the bump 500 contacts a feature, such asa proximal edge 260, a bump, a lip, or similar protrusion of the shuttle160. Further translation of the shuttle 160 causes the bump 500 to forcethe shuttle segments 161, 163 apart, providing tactile feedback in theform of increased resistance to the user of the rotation mechanism 90.In certain implementations, the bump 500 may be substituted with anO-ring or similar structure retained on the shaft 175, such asillustrated in FIGS. 13-18B. In such implementations, the O-ring mayfunction similarly to the bump 500 of FIGS. 24-26B by, among otherthings, resisting proximal translation of the shuttle 160 such thatproximal translation of the shuttle 160 requires separation of the 161,163. Deformation of the O-ring may also occur such that the increasedrotational resistance provided to a user results from a combined effectof the O-ring deformation and the behavior of the garter springs 502,504.

As shown in FIG. 24A, the shuttle 160 may include a proximal innercircumferential chamber 310 at the proximal end of the shuttle and adistal inner circumferential chamber 315 at the distal end of theshuttle. Each chamber 310, 315 may include a pair of spaced-apartradially inwardly extending lips, bumps, or similar features. In theexample of FIG. 24A, these lips include an outer lip and an inner lip.Specifically, for the proximal chamber 310, the outer lip is a proximalouter lip 320 at the proximal edge of the shuttle 160, and the inner lipis a distal inner lip 325 distal the proximal outer lip 320. The lips320, 325 are spaced-apart from each other and radially inwardly projectfrom an inner cylindrical surface 327 of the proximal chamber 310. Forthe distal chamber 315, the outer lip is a distal outer lip 330 at thedistal edge of the shuttle 160, and the inner lip is a proximal innerlip 335 proximal the distal outer lip 330. The lips 330, 335 arespaced-apart from each other and radially inwardly project from an innercylindrical surface 337 of the distal chamber 315.

When the shuttle 160 is in the most distal location along the shaft 175of the torque portion 130 of the handle 108, the distal spring 155(shown in FIGS. 13 and 14) is compressed between the distal ring 295 ofthe shuttle 160 and an interior wall 135 immediately proximal theratchet assembly 150. On account of the pitch direction of the helicalpartial thread 185 on the shaft 175 of the torque portion 130, anddespite the distal spring 155 biasing the shuttle proximally such thatits distal rim 265 is kept in abutting contact with the thread 185, thethread 185 of the shaft 175 does not engage the interior threads 250 ofthe shuttle 160 as long as the torque portion 130 is rotatedcounter-clockwise (CCW), the thread 185 simply riding along the distalrim 265 of the shuttle 160. Thus, the torque portion 130 and the linearmember 120 extending distally therefrom (as shown and discussed in thecontext of FIG. 13), can infinitely rotate CCW and cause the leadlesspacemaker 102 to rotate CCW, as can be understood from FIG. 1, such thatthe helical anchor on the distal end of the leadless pacemaker willunscrew from cardiac tissue in which it may be imbedded. The CCWrotation causes the ratchet assembly 150 to generate anincremental/stepped tactile sensation in the grip 180 of the torqueportion 130 of the handle 108.

Conversely, on account of the pitch direction of the helical partialthread 185 on the shaft 175 of the torque portion 130, and because thedistal spring 155 (shown in FIGS. 13 and 14) biases the shuttleproximally such that its proximal rim 265 is kept in abutting contactwith the thread 185, the thread 185 of the shaft 175 engages theinterior threads 250 of the shuttle 160 once the torque portion 130 isrotated clockwise (CW) and the shaft thread 185 encounters one of themultiple thread-start locations 255 intersecting the proximal rim 265.Once threaded engagement occurs between the shaft thread 185 and theshuttle threads 250, further CW rotation of the torque portion 130 willcause the shuttle 160 to proximally displace along the shaft 175. As canbe understood from FIGS. 1 and 13, the CW rotation of the torque portion130 and the linear member 120 extending distally therefrom rotates theleadless pacemaker 102 CW such that the helical anchor on the distal endof the leadless pacemaker will screw into cardiac tissue contacting thehelical anchor. The CW rotation causes the ratchet assembly 150 togenerate an incremental/stepped tactile sensation in the grip 180 of thetorque portion 130 of the handle 108.

Continued CW rotation of the torque portion 130 further proximallydisplaces the shuttle 160 along the shaft 175 as the shuttle threads 250move proximally along the rotating shaft thread 185, which is confinedto rotation about the longitudinal axis of the shaft and does notdisplace distal-proximal. As the shuttle moves along the shaft, theshuttle guide members 240 linearly displace proximally along therespective guide slots 270. In some embodiments where the guide slots270 daylight through the exterior wall 140 of the housing 125, thedisplacement of the shuttle guide members 240 can be observed throughthe windows created by the guide slots 270 in the exterior wall 140 ofthe housing 125, similar to that discussed above with respect to FIGS.2, 4 and 5.

As the CW rotation of the torque portion 130 causes the shuttle 160 todisplace proximally from the most distal location, the tactile sensationand resistance felt in the grip 180 of the torque portion 130 willremain constant as provided by the ratchet assembly 150 until theshuttle 160 is sufficiently proximally displaced such that the proximalboundary of the proximal outer lip 320, which is at the shuttle proximaledge 260, encounters the bump 500, as illustrated in FIGS. 24A and 24B.At this time, the resistance felt in the grip 180 of the torque portion130 will begin to gradually increase as the radially inwardly projectinglip 320 travels across the bump 500. More specifically, the bump 500causes separation of the shuttle segments 161, 163, which isincreasingly resisted by the proximal garter spring 504 as theseparation increases.

In one embodiment, the number of CW rotations needed to displace theshuttle from a most distal position to the stopped position shown inFIGS. 24A and 24B will be two and one-quarter rotations of the grip 180of the torque portion 130 of the handle 108. This two and one-quarterrotations is based on what is considered to be a typical number of turnsof the helical anchor of the leadless pacemaker to cause the helicalanchor to fully imbed in the cardiac tissue without over-penetrating thecardiac tissue. In other embodiments, the number of rotations requiredto displace the shuttle between the most distal location and thelocation depicted in FIGS. 24A-24B will be more or less than two andone-quarter rotations.

Once the proximal boundary of the proximal outer lip 320, which is atthe shuttle proximal edge 260, encounters the bump 500, as illustratedin FIGS. 24A and 24B, this contact will notify the physician that theprescribed number of rotations of the helical anchor of the leadlesspacemaker has been reached. At this point, should the physician decideadditional CW rotations of the helical anchor of the leadless pacemakerare necessary to achieve a desired level of fixation to the cardiactissue, as can be understood from FIGS. 25-26, continued CW rotations ofthe grip 180 of the torque portion 130 of the handle 108 will continueto proximally displace the shuttle 160 and drive the radially inwardlyprojecting lip 320 at the shuttle proximal edge 260 completely over andproximally past the bump 500 such that the bump 500 is received in theproximal inner circumferential chamber 310 as indicated in FIG. 26.

In certain implementations, such as that illustrated in FIGS. 24A-26,the bump 500 may permit reversal of the shuttle 160. For example, afterthe radially inwardly projecting lip 320 passes a peak of the bump 500,the grip 180 may be rotated CCW to cause the shuttle 160 to translate inthe distal direction. As the shuttle 160 distally translates, the bump500 will again the shuttle 160 and, as the shuttle further translates,separation of the shuttle segments 161, 163, resulting in tactilefeedback as previously described.

The warning aspect of the rotation mechanism 90 of FIGS. 24A-26 may beadapted to provide multiple and varying warnings to a physician inresponse to rotation of the leadless pacemaker. For instance, additionalbumps 500 could be incrementally located along the shaft 175 proximalfrom a first bump such that each bump causes a change in the rotationalresistance of the grip 180. Such a sequence of bumps may be distributedalong the shaft 175 such that each bump corresponds to a specific numberof rotations of the leadless pacemaker. The shuttle 160 may also includemultiple lips or similar features that contact and must pass over one ormore bumps disposed along the shaft 175. The shape of the bump 500 orlip of the shuttle 160 may also be altered to change the resistanceencountered during rotation of the grip 180. For example, the overallheight of the bump 500 or lip may be increased or decreased to modifythe peak rotational force required to overcome the bump 500.

Similarly, the length and slope of the bump 500 or lip may be altered tochange the rate at which the rotational resistance of the grip 180increases. Resistance to rotation of the grip 180 may also be modifiedby changing the inward force provided by the compliant members 502, 504to the shuttle segments 161, 163. For example, one or more of thematerial, thickness, quantity, and placement of the compliant members502, 504 may be modified to vary the resistance to rotation of the grip180 provided by the compliant members 502, 504.

G. Handle with Rotation Mechanism Employing Elastomeric Bumper

To begin a discussion of yet another version of the rotation mechanism90 of the handle 108 of the leadless pacemaker delivery system of FIG.1, reference is now made to FIG. 27, which is an isometric view of thehandle 108 with a portion of a housing 125 of the handle 108 removed toreveal the alternative rotation mechanism 90 enclosed therein.

As can be understood from a comparison of FIG. 27 to FIGS. 13-14, thealternative version of the rotation mechanism 90 and the surroundingelements of the handle 108 and leadless pacemaker delivery system of theversion of FIG. 25 share the majority of elements and operation asdiscussed above with respect to FIGS. 13-14, except that the springs155, 165 disposed between the shuttle 160 and the interior walls 135have been removed and replaced with elastomeric bumpers 490, 495.Accordingly, the preceding discussion of FIGS. 13-14 is equallyapplicable to the version of the rotation mechanism 90 and surroundingelements of the handle 108 shown in FIG. 27, except as will now bespecifically discussed with respect to FIG. 27.

As indicated in FIG. 27, a distal bumper 490 and a proximal bumper 495are retained against distal and proximal interior walls 135 of thehousing 180. As shown in FIG. 25, each of the distal bumper 490 and theproximal bumper 495 extend circumferentially around, and are coaxialwith, the shaft 175 of the torque portion 130. The bumpers 490, 495 aredisposed between the shuttle 160 and corresponding distal and proximalinternal walls 135 of the handle 108 such that as the shuttle 160approaches its distal and proximal extents within the handle 108, thedistal and proximate bumpers 490, 495 are compressed between the shuttle160 and the distal and proximal internal walls 135, respectively. In analternative implementation, one or both of the distal bumper 490 and theproximal bumper 495 may instead be retained on distal and proximal endsof the shuttle 160, respectively, and perform similar functions asdescribed below. In still other implementations, the distal bumper 490may be omitted.

When the shuttle 160 is in the most distal location along the shaft 175of the torque portion 130, the distal bumper 490 is compressed betweenthe shuttle 160 and an interior wall 135 immediately proximal theratchet assembly 150. On account of the pitch direction of the helicalpartial thread 185 on the shaft 175 of the torque portion 130, anddespite the distal compliant member 390 biasing the shuttle 160proximally such that its distal rim 265 (see, e.g., FIGS. 8A and 8B) iskept in abutting contact with the thread 185, the thread 185 of theshaft 175 does not engage the interior threads 250 of the shuttle 160 aslong as the torque portion 130 is rotated counter-clockwise (CCW), thethread 185 simply rides along the distal rim 265 of the shuttle 160.Thus, the torque portion 130 and the linear member 120 extendingdistally therefrom, as shown in FIG. 3, can infinitely rotate CCW andcause the leadless pacemaker 102 to rotate CCW, as can be understoodfrom FIG. 1, such that the helical anchor on the distal end of theleadless pacemaker will unscrew from cardiac tissue in which it may beimbedded.

Conversely, on account of the pitch direction of the helical partialthread 185 on the shaft 175 of the torque portion 130, and because thedistal compliant member 390 biases the shuttle 160 proximally such thatits proximal rim 265 is kept in abutting contact with the thread 185,the thread 185 of the shaft 175 engages the interior threads 250 of theshuttle 160 once the torque portion 130 is rotated clockwise (CW) andthe shaft thread 185 encounters one of the multiple thread-startlocations 255 intersecting the proximal rim 265. Once threadedengagement occurs between the shaft thread 185 and the shuttle threads250, further CW rotation of the torque portion 130 will cause theshuttle 160 to proximally displace along the shaft 175. As can beunderstood from FIGS. 1 and 3, the CW rotation of the torque portion 130and the linear member 120 extending distally therefrom rotates theleadless pacemaker 102 CW such that the helical anchor on the distal endof the leadless pacemaker will screw into cardiac tissue contacting thehelical anchor. In certain implementations, the CW rotation causes theratchet assembly 150 to generate an incremental/stepped tactilesoft-stop sensation in the grip 180 of the torque portion 130 of thehandle 108.

As the CW rotation of the torque portion 130 causes the shuttle 160 todisplace proximally from the most distal location, the tactile sensationand resistance felt in the grip 180 of the torque portion 130 willremain constant as provided by the ratchet assembly 150 until theshuttle 160 is sufficiently proximally displaced such that the proximalface of the shuttle 160 contacts the proximal bumper 495, which isdisposed adjacent a proximal interior wall 135. Further CW rotation ofthe torque portion 130 causes compression of the proximal bumper 495and, as a result, increased resistance to continued movement of theshuttle 160 in the proximal direction. Accordingly, a user of therotation mechanism 90 receives an initial warning in the form ofincreased resistance to rotation of the torque portion 130. Afterinitial contact between the proximal compliant member 195 and theproximal internal wall 135, a user of the rotation mechanism 90 maydecide whether additional CW rotations of the helical anchor of theleadless pacemaker are necessary to achieve a desired level of fixationto the cardiac tissue. If additional CW rotations are applied, therotational resistance provided by the proximal bumper 495 may increaseaccordingly.

Each of the bumpers 490, 495 may be made of materials such as, forexample, metals, compressible polymers, and/or etc. While depicted asbeing solid tubules in the implementation of FIG. 27, the bumpers 490,495 are not limited to such a shape. For example, in certainimplementations, the compliant member 490, 495 may be helical springs ormay include internal or external grooves, cutouts, or combinationsthereof. In certain instances, the bumpers 490, 495 may include multiplesections, each of which may be composed of a different material or havea different geometry. In light of the foregoing, the warning aspect ofthe rotation mechanism 90 of FIG. 27 may be adapted by modifying thematerial and structure of the bumpers 490, 495. For example, a highrotational resistance and a high rate of rotational resistance increasemay be achieved by using bumpers composed of relatively stiff materials.Rotational resistance may also be modified by forming grooves or cutouts(including, without limitation, longitudinal, circumferential, andhelical grooves or cutouts) on the bumper, with the relative spacing,depth, and width of the grooves or cutouts modifying the overallstiffness of the bumper.

H. Handle with Electronic Warning Mechanism

Reference is now made to FIGS. 28A-28B which are cross-sectional sideviews of another version of a handle 108 with a portion of a housing 125of the handle 108 removed to reveal a rotation mechanism 90 according tothe present disclosure.

As can be understood from a comparison of FIG. 27 to FIGS. 1-27, thealternative version of the rotation mechanism 90 and the surroundingelements of the handle 108 and leadless pacemaker delivery system of theversion of FIGS. 28A-28B share the majority of elements and operation asdiscussed above with respect to FIGS. 1-27, except that the springs 155,165 disposed between the shuttle 160 and the interior walls 135 havebeen replaced with a distal bellows 1005, and a proximal bellows 1010,respectively. The version of the handle 108 shown in FIGS. 28A-28Bfurther incorporate electrical circuitry adapted to provide feedback toa user in response to the position of the shuttle 160 within the housing108. Accordingly, the preceding discussion of FIGS. 1-27 is equallyapplicable to the version of the rotation mechanism 90 and surroundingelements of the handle 108 shown in FIGS. 28A-28B, except as will now bespecifically discussed with respect to FIGS. 28A-28B.

As indicated in FIGS. 28A-28B, a distal bellows 1005 and a proximalbellows 1010 are coupled to distal and proximate ends of a shuttle 160,respectively. The handle 108 includes a torque portion 130 that, whenrotated, causes rotation of a leadless pacemaker coupled to the handle108 as well as translation of the shuttle 160 within the handle 108. Forexample, in certain implementations, clockwise (CW) rotation of thetorque portion 130 causes the shuttle 160 to move proximally whilecounterclockwise (CCW) rotation of the torque portion 130 causes theshuttle 160 to move distally. In certain implementations, the handle 108may include a ratchet assembly (such as the ratchet assembly of FIGS. 7Aand 7B and previously discussed in this disclosure) that providestactile feedback to a user of the handle 108 as the torque portion 130is rotated. As previously described in this disclosure, other tactilefeedback features may also be incorporated in the handle 108 to providevarying resistance to rotation of the torque portion 130 and tactilewarnings to a user as the shuttle 160 translates within the housing 108.In other implementations, the shuttle 160 may be substituted with analternative body translatable within the housing 108 in response torotation of the torque portion 130.

As illustrated by the difference between FIGS. 28A and 28B, the proximalbellows 1010 is constructed into the handle 108 such that the proximalbellows 1010 compresses as the shuttle 160 approaches a proximal end ofthe handle 108. Such translation also causes expansion of the distalbellows 1005. Similarly, as the shuttle 160 is made to translatedistally, the distal bellows 1005 is compressed and the proximal bellows1010 expands. In certain implementations, the proximal bellows 1010 maybe spring bellows such that as the proximal bellows 1010 is compressed,the amount of resistance to additional compression and, as a result,additional rotation of the torque portion 130 may be increased, therebyproviding tactile feedback relative to the position of the shuttle 160.

The handle 108 of FIGS. 28A-28B includes electrical components adaptedto determine the position of the shuttle 160 within the housing 108 andprovide feedback to a user of the handle 108. More specifically, theelectrical components measure or otherwise determine the position of theshuttle 160 within the housing 108 relative to one or more predeterminedshuttle positions corresponding to a number of rotations of the torqueportion 130. Feedback and warnings are then provided to a user based onthe position of the shuttle 160, such as through illumination of one ormore LEDs 1020 visible to the user.

In the implementation illustrated in FIGS. 28A-28B, the handle 108 iscommunicatively coupled to a computing device (CPU) 1015 configured tosend and receive signals to and from the handle 108. In certainimplementations, the computing device 1015 may be incorporated into thehandle 108. The computing device 1015 may include at least one processorand memory that includes instructions executable by the processor toreceive signals from the handle 108 and to determine a position of theshuttle 160 based on the received signals. The computing device 1015 maythen transmit signals to the handle 108 that cause appropriate feedbackto be provided to the user. For example, such signals from the computingdevice 1015 may cause one or more LEDs 1020 to illuminate. In otherimplementations, the computing device 1015 may instead be replaced byother circuitry configured to activate one or more feedback devicesbased on the position of the shuttle 160 within the housing 108. Forexample, in one implementation, such a circuit may include a switchcoupled to a power source that, when closed by action of the shuttle160, causes an LED to illuminate.

In the implementation illustrated in FIGS. 28A-28B, each of the distalbellows 1005 and the proximal bellows 1010 are constructed of anelectrically conductive material such that the resistance of the distalbellows 1005 ad the proximal bellows 1010 vary as the bellows 1005, 1010are compressed and expanded. The distal bellows 1005 and the proximalbellows 1010 are coupled to the computing device 1015 by a first lead1035 and a second lead 1040 such that the computing device 1015 maymonitor the resistances of the bellows 1005, 1010 and determine acorresponding position of the shuttle 160 within the housing 108. Thecomputing device 1015 may also be coupled to the LEDs 1020 such that thecomputing device 1015 may illuminate one or more of the LEDs in responseto the position of the shuttle 160. For example, in one implementation,the LEDs may be color coded (e.g., green, yellow, red) to indicate therelative proximity of the shuttle 160 to a predetermined location withinthe housing 108 and the computing device 1015 may selectively illuminatethe LEDs based on the position of the shuttle 160.

In other implementations, switches, variable resistors, and othercomponents may be used to determine the location of the shuttle 160within the housing 108. For example, one or more limit switches may bedisposed along the housing 108 such that as the shuttle 160 translateswithin the housing 108, the shuttle 160 closes the switches, indicatingits position within the housing 108. Switch elements may also beintegrated into the distal or proximal bellows 1005, 1010 such that theswitches close in responses to the distal or proximal bellows 1005, 1010being compressed or expanded. Movement of the shuttle 160 within thehousing 108 resulting from rotation of the torque portion 130 may alsocauses changes to a variable resistance element (e.g. a potentiometer)such that the position of the shuttle 160 may be determined in responseto measuring the resistance of the variable resistance element.

The use of one or more LEDs as a warning mechanism is intended only asan example and other warning mechanisms may be used to alert a user whenthe shuttle 106 reaches a position within the handle 108 correspondingto a specific number of rotations. For example, the handle 108 mayinclude other components adapted to produce other types of feedback,such as vibrations or audible signals, in response to the shuttle 160reaching certain positions within the handle 108 that correspond topredetermined numbers of rotations of a leadless pacemaker. Suchfeedback may be progressive such that the character or intensity of thefeedback may vary based on the proximity of the shuttle 160 to one ormore of the predetermined positions. For example, the volume or tone ofan audible feedback signal or the intensity of a vibration may increaseas the shuttle 160 approaches a predetermined position. In still otherimplementations, the handle 108 may include a screen or display, such asa liquid crystal display (LCD), on which information may be provided tothe user of the handle 108. Such information may include, for example, avisual indicator or other visual indicator (including an actual number)corresponding to the number of rotations of the torque portion 130 ofthe handle 108.

To facilitate use of the handle 108 illustrated in FIGS. 28A-28B, aninternal or external power source may be included in or otherwisecoupled to the handle 108. For example, in certain implementations, thehandle 108 may include a battery or similar internal power source whichmay be rechargeable and/or replaceable. Alternatively, the handle 108may include a cord to electrically couple the handle 108 to an externalpower source, such as, without limitation, an external battery, a powerpack, and a wall socket.

I. Example Feedback Profiles

FIGS. 27A-I illustrate different feedback profiles that may beimplemented in leadless pacemaker delivery systems according to thepresent disclosure. In general, each feedback profile shows theresistance to rotation of a component of the leadless pacemaker deliverysystems, such as the torque portion 130 of the handle 108, relative tothe rotational position of the component. The example feedback profilesare intended as examples only and are not intended to limit the types offeedback profiles that may result from implementations of the presentdisclosure.

For purposes of this discussion, rotation is assumed to be applied by auser to a torque portion, such as torque portion 130, of a leadlesspacemaker delivery system in accordance with this disclosure.

FIG. 29A is a first feedback profile illustrating one full rotation of atorque portion of a first leadless pacemaker delivery system. As shownin FIG. 29A, a base rotational resistance is provided over the majorityof the rotation, however, as a full rotation nears completion, therotational resistance rises exponentially and continues to increases themore a full rotation is exceeded.

FIG. 29B is a second feedback profile illustrating two full rotations ofa torque portion of a second leadless pacemaker delivery system. Asshown in FIG. 29B, a based rotational resistance is provided for themajority of each rotation, however, the rotational resistance isperiodically increased to indicate every half rotation (i.e., every 180degrees).

FIG. 29C is a third feedback profile illustrating one full rotation of atorque portion of a third leadless pacemaker delivery system. Similar tothe feedback profile illustrated in FIG. 29A, a base rotationalresistance is provided over the majority of the rotation, however, as afull rotation nears completion, the resistance rises to provide anindication of the rotation to a user. In contrast to the feedbackprofile of FIG. 29A, additional rotation of the rotational resistancecauses the rotational resistance to fall back to the base rotationalresistance.

FIG. 29D is a fourth feedback profile illustrating one full rotation ofa torque portion of a fourth leadless pacemaker delivery system. Similarto the feedback profile illustrated in FIG. 29C, a base rotationalresistance is provided over the majority of the rotation, however, as afull rotation nears completion, the resistance rises to provide anindication of the rotation to a user. In contrast to the feedbackprofile of FIG. 29D, the increased rotational resistance is maintainedfor approximately one quarter rotation before returning to the baserotational resistance.

FIG. 29E is a fifth feedback profile illustrating two full rotations ofa torque portion of a fifth leadless pacemaker delivery system. Similarto the feedback profile illustrated in FIG. 29D, a base rotationalresistance is increased and maintained as a first rotation is completed.The increased rotational resistance is maintained for approximately onehalf turn before returning to the base rotational resistance. A secondincrease in the rotational resistance then occurs in response to thecompletion of a second rotation.

FIG. 29F is a sixth feedback profile illustrating one full rotation of atorque portion of a sixth leadless pacemaker delivery system. Thefeedback profile illustrated in FIG. 29F combines aspects of thefeedback profiles of FIG. 29A and that of FIG. 29D. More specifically, abase rotational resistance is increased in response to completion of afirst rotation. The increased rotational resistance is then maintainedfor approximately one quarter rotation before the rotational resistancecontinues to increase exponentially.

FIG. 29G is a seventh feedback profile illustrating one full rotation ofa torque portion of a seventh leadless pacemaker delivery system.Similar to the feedback profile illustrated in FIG. 29D, a baserotational resistance is increased and maintained as a first rotation iscompleted. The increased rotational resistance is maintained forapproximately one half turn before returning to the base rotationalresistance. However, the feedback profile of FIG. 29G further includes abrief increase in rotational resistance at approximately three quarterrotations. Accordingly, the brief increase may server as a preliminaryindication that a full rotation is near completion.

FIG. 29H is an eighth feedback profile illustrating one full rotation ofa torque portion of an eighth leadless pacemaker delivery system. Incontrast to the previous feedback profiles of FIGS. 29A-29G, the eighthfeedback profile includes a decrease in rotational resistance from abase rotational resistance to a reduced rotational resistance inresponse to completing a full rotation.

The foregoing example feedback profiles were described in the context ofone or two full rotations for clarity only. Accordingly, the illustratedfeedback profiles or variations thereof may be modified such that theyoccur over a quantity of rotations other than one or two full rotations.For example and as previously disclosed in the context of FIGS. 10A-11B,fixation of a leadless pacemaker into cardiac tissue may generallyrequire two and one quarter rotations. As a result, the foregoingfeedback profiles may be offset or modified to include a change inrotational resistance corresponding to two and one quarter rotations orotherwise be based around a two and one quarter rotation target.

While the above-described rotation mechanism and its various warningmechanisms are discussed in the context of a leadless pacemaker deliverydevice, those skilled in the art will readily understand that therotation mechanism and its various warning mechanisms may be employedwith other medical devices such as, for example, minimally invasivesurgery (MIS) tools, including for example, endoscopic devices,laparoscopic devices, and similar devices. The rotation mechanism andits various warning mechanisms may be employed with tools for thedelivery and fixation of a standard implantable lead, for the delivery,fixation and/or actuation of other implantable devices. Example ofactuating an implanted devices include turning on an implantable device,opening a valve, causing a device to change states, etc., wherein any ofthese actuations or operational settings may be achieved via rotation ofan element of the implanted device via the above-described rotationmechanism, and the rotation should be measured to prevent damage to thedevice and/or body tissue, the measured rotation being made possible viathe warning mechanisms described herein.

The foregoing merely illustrates the principles of the invention.Various modifications and alterations to the described embodiments willbe apparent to those skilled in the art in view of the teachings herein.It will thus be appreciated that those skilled in the art will be ableto devise numerous systems, arrangements and methods which, although notexplicitly shown or described herein, embody the principles of theinvention and are thus within the spirit and scope of the presentinvention. From the above description and drawings, it will beunderstood by those of ordinary skill in the art that the particularembodiments shown and described are for purposes of illustrations onlyand are not intended to limit the scope of the present invention.References to details of particular embodiments are not intended tolimit the scope of the invention.

What is claimed is:
 1. A medical tool comprising a handle including: ahousing; a torque portion operably coupled to the housing and rotatablerelative to the housing, the torque portion including a shaft includingan outer circumferential surface and a helical thread portion radiallyoutwardly extending from the outer circumferential surface of the shaft;a shuttle displaceable along the shaft via threaded interaction with thehelical thread portion; and a warning mechanism interacting with theshuttle that provides a tactile indication when the torque portion hasrotated a number of rotations.
 2. The medical tool of claim 2, whereinthe shaft includes a first end and a second end opposite the first end,the shaft being capable of infinite rotation in a first directionwithout causing further displacement of the shuttle along the shafttoward the first end when the shuttle is at a first location near thefirst end, but rotation of the shaft in a second direction opposite thefirst direction when the shuttle is at the first location causes theshuttle to displace along the shaft towards the second end.
 3. Themedical tool of claim 1, wherein the shaft is capable of infiniterotation in the second direction without causing further displacement ofthe shuttle along the shaft toward the second end when the shuttle is ata second location near the second end, but rotation of the shaft in thefirst direction when the shuttle is at the second location causes theshuttle to displace along the shaft towards the first end.
 4. Themedical tool of claim 2, further comprising a first biasing element thatbiases the shuttle towards the second end when the shuttle is at thefirst location, and a second biasing element that biases the shuttletowards the first end when the shuttle is at the second location.
 5. Themedical tool of claim 1, wherein the warning mechanism includes anO-ring on the shaft that is deflected by the shuttle as the shuttlepasses over the O-ring, the deflection providing the tactile indication.6. The medical tool of claim 5, wherein the O-ring is deflected by a lipof the shuttle.
 7. The medical tool of claim 6, wherein the shuttleincludes a region inward of the lip that allows the O-ring to return toits non-deflected shape within the confines of the shuttle.
 8. Themedical tool of claim 5, wherein the tactile indication includes aperiod of increased rotational resistance at the torque portion as theO-ring is being deflected by the shuttle.
 9. The medical tool of claim1, wherein the medical tool is a delivery system for delivering aleadless pacemaker into cardiac tissue.
 10. A medical tool comprising arotation mechanism including a warning feature that provides a tactileindication when the rotation mechanism has achieved a number ofrotations.
 11. The medical tool of claim 10, wherein the tactileindication is provided by compression of an O-ring on a shaft of therotation mechanism by a shuttle that displaces along the shaft and isdriven by the shaft.
 12. The medical tool of claim 10, wherein thetactile indication includes a period of increased rotational resistanceat a torque portion of a handle of the tool.
 13. The medical tool ofclaim 10, wherein a drive shaft of the rotation mechanism includes afirst end and a second end opposite the first end, the drive shaft beingcapable of infinite rotation in a first direction without causingfurther displacement of the shuttle along the drive shaft toward thefirst end when the shuttle is at a first location near the first end,but rotation of the drive shaft in a second direction opposite the firstdirection when the shuttle is at the first location causes the shuttleto displace along the drive shaft towards the second end.
 14. Themedical tool of claim 11, wherein the drive shaft is capable of infiniterotation in the second direction without causing further displacement ofthe shuttle along the drive shaft toward the second end when the shuttleis at a second location near the second end, but rotation of the driveshaft in the first direction when the shuttle is at the second locationcauses the shuttle to displace along the drive shaft towards the firstend.
 15. The medical tool of claim 14, wherein a first biasing elementof the rotation mechanism biases the shuttle towards the second end whenthe shuttle is at the first location, and a second biasing element ofthe rotation mechanism biases the shuttle towards the first end when theshuttle is at the second location.
 16. The medical tool of claim 10,wherein the medical tool is a delivery system for delivering a leadlesspacemaker into cardiac tissue.